CbB 2019.09 -> Sonar 2025.07: audio glitches when clicking on tracks while project plays, ProChannel likely culprit

[Jan]

After upgrading from CbB 2019.09 to Sonar 2025.07 I sadly noticed that when the project plays merely clicking on an AUDIO or INSTRUMENT track (not resizing it or anything) produces an audible glitch to the point where some of my MeldaProduction tempo-synced effects go out of sync or some MIDI notes get canceled (in this particular case it was a Sylenth1 arp). By "clicking on a track" I mean clicking on the track strip in the track list (empty area or its number on the left). Clicking on CLIPS (first in one track, then in another) does not produce this effect AFAIK. Clicking on MIDI tracks does not seem to produce this effect.

The project has approx 60 tracks and as far as VSTs go it uses multiple (approx. 20) instances of Shortcircuit (light-weight sampler, 32-bit, running on JBridge, switching to default 32-bit bridge does not change anything) for drums, 2 Sylenth1 instances, one Spire and one Dune. FX: mostly MeldaProduction MTremolo/MTremoloMB for pumping effects, MRhythmizer (hi-hat stutters), MEqualizer, also MWaveShaper. A couple of busses, 1 or 2 Aux tracks. Nothing too fancy. No dynamics processing, no limiter, etc. The CPU does not look taxed very much. The same issue occurs on other similarly sized projects (I haven't been able to reproduce this on a blank project with just a couple of tracks - perhaps the number of tracks/plugins makes Sonar behave like this)

Attached files:

rec1 - audio output of the project with me clicking. The glitches might not be super audible, but they are there. You can hear at around 14 second mark the arp stops playing completely (probably missed a note-on event), and you can later hear how the pumping effect goes out of sync.

sine - I put an additional track with a simple A440 sine, soloed it and started clicking on tracks while the project was playing. The glitches are pretty audible.

One glitch = one click (at times I clicked quite rapidly)

Scarlett 6i6 2nd Gen, firmware 1583, driver 4.124.3 (newest, freshly updated to see if it makes any change - it doesn't)
i7-8700, 32GB RAM, Windows 10
driver mode: ASIO, Use multiprocessing engine: on, plugin load-balacing: on, use MMCSS: on, enable MMCSS on ASIO: off (flipping LB/MMCSS/MMCSS on ASIO doesn't change anything)

This has never *) been an issue with CbB, which is running fine on a 128 samples buffer. Increasing the buffer size to even 512 samples (way beyond my comfort zone) doesn't seem to change anything. CbB has just started displaying "activation required within 11 days". Not great

*) well, at least not when simply clicking on tracks. It would however produce similar effect when clicking Mute/Solo while playing - temporary glitch, MTremolo going out of sync until playback is restarted. I just figured out "that's just the way it is" and learned to live with that. However having this happen when simply clicking on a track (to change eq, whatever) is a dealbreaker.

P.S. Just noticed - while writing this - that when I came back to Sonar and hit "Play" the window would update only once per second (a slideshow essentially). Not sure what caused it. Maybe related?

Edited yesterday at 12:27 PM by Jan
clarification of likely cause in the topic after investigation

[Jan]

Some additional info - ThreadSchedulingMode was set to 1, changing to 2 or 3 - no difference. The AUD.INI files from CbB and Sonar 2025.07 are almost identical except

DefaultAudSnapOfflineStretchMethod (was 12, is 11, obviously, because Elastique)
WaveInID (was 2, is 0)
LatencyMsec (was 5, is 2.902494 - that's an odd one, but as I said changing the buffer size even to 512 samples doesn't fix this)
TransDetectorModel (was 1, is 2)
AutomationDecimationMsec (was 50, is 5)

and a bunch of new entries in Sonar's file

TransDetectorUpgraded=1
CoreSelectionMethod=1
ExcludeEfficiencyCores=0
PluginLoadBalancingThreadCount=0
EnableMMCSSforASIO=0
MaskDropoutDetection=0
RestartEngineAfterDropout=1
StopEngineOnASIOPanelOpen=1

[reginaldStjohn]

Check that your cakewalk project folders are excluded from anti-virus scans. Also, check that a virus scan is not happening. You may have to disable anti-virus or search indexing to see if this is the cause.

[Jan]

1 hour ago, reginaldStjohn said:

Check that your cakewalk project folders are excluded from anti-virus scans. Also, check that a virus scan is not happening. You may have to disable anti-virus or search indexing to see if this is the cause.

I'm using the exact same project folders as in CbB. There's no AV running. I tested this multiple times - CbB plays fine, Sonar glitches. And this happens only when clicking on a track, when I don't touch anything everything plays fine. There are no visible CPU spikes or anything.

[Jan]

Another interesting piece of information:

The glitch does NOT happen on INSTRUMENT tracks when "MIDI" properties view is on.

So it looks like the glitches only occur when a Track Inspector is attempting to display AUDIO-related information when one switches from one track to another (as it happens when switch between 1) audio tracks, 2) aux tracks and 3) instrument tracks when "Audio" view is enabled)

 

The glitch also happens when clicking "show/hide pro-channel", "show/hide track properties", "show/hide tempo inspector", "show/hide arranger inspector", "show/hide clip properties" (but only in the cases listed above, so on 1) audio tracks,  2) aux tracks and 3) instrument tracks when "Audio" view is enabled, does not happen on "Midi" view)

Edited Thursday at 08:51 PM by Jan

[Jan]

And one more which might limit the number of potential root causes:

The glitch does NOT happen when Track Inspector is minimized. So it definitely has to do with querying/displaying audio properties of audio track/aux track/instrument track. I thought maybe it was the spectrum analyzer (which the 2019.09 doesn't have) but turning it off did not help.

Edited Thursday at 08:55 PM by Jan

[Jan]

I think I might have found the likely culprit - when the ProChannel is unchecked the glitch does NOT seem to occur. This would explain why it wasn't happening on MIDI tracks and when in "MIDI" view of Instrument track (they have no ProChannel to display). So I guess this is potentially a temporary fix for me, although that's still a bug and regression from 2019.09...

[hydrogen 786]

🔍 Summary of the Issue:

After upgrading to Sonar 2025.07, clicking on audio or instrument tracks (just selecting them, not editing) during playback causes audio glitches, including:

Out-of-sync tempo-synced FX (e.g., MTremolo, MRhythmizer)

MIDI note dropouts (e.g., arp in Sylenth1 stops playing)

This did not occur in CbB (Cakewalk by BandLab) even under low buffer settings.

Glitches do not happen when clicking on clips or MIDI tracks.

Issue occurs in larger projects (~60 tracks, 20+ plugins), not in blank/test projects.

Tried: buffer size increase, plugin bridging changes, driver updates, all common settings (multiprocessing, MMCSS, plugin load balancing).

Audio interface: Focusrite Scarlett 6i6 Gen 2 (ASIO, latest driver).

Hardware and CPU usage are not bottlenecks.

🧠 What Might Be Going On

1. GUI-to-Audio Thread Interference

Sonar may have introduced changes in how the track selection GUI action is handled — potentially interrupting real-time audio scheduling, especially in heavy projects.

Clicking on a track likely triggers focus changes, GUI refresh, and potentially UI-linked audio processing.

If this is handled poorly (e.g., synchronously or on the main thread), it can lead to audio glitches, especially with tempo-synced effects or note triggers.

2. VST Bridging Stability

Your use of multiple bridged 32-bit plugins (Shortcircuit) via JBridge may be playing a role. Even if they ran fine before, the host’s internal threading and resource management may now interact differently post-upgrade.

Clicking around the UI might be causing plugin thread contention or timing mismatches in the new host environment.

Bridged plugins (especially older 32-bit ones) are notoriously sensitive to such changes.

3. Project Size & Complexity

While your project isn't using heavy FX or CPU, the sheer number of VST instances and tracks might be pushing Sonar's real-time handling to a threshold, where any UI activity can cause minor timing disruptions.

4. Bug in Sonar 2025.07

Given this didn't happen in CbB and does happen reproducibly in Sonar 2025.07 (but not in minimal projects), this could be a regression or performance bug in the new version.

✅ What You Can Try Next

Here are focused suggestions you can try, and what to report if contacting Sonar/Cakewalk support:

🛠️ Technical Workarounds:

Disable Waveform Preview / Track Meter Animations Temporarily

These can tie into the GUI refresh and cause glitches.

Go to Preferences > Display and disable unnecessary visuals during playback.

Minimize GUI Load

Try switching to the Console View or a different layout that doesn’t actively draw 60+ tracks at once.

Keep fewer views open (e.g., close Inspector, Browser, etc.) during playback.

Try Running Sonar as Administrator

Helps avoid OS-level priority mismatches, particularly with MMCSS.

Create a Copy of the Project Without Bridged Plugins

Replace or remove the Shortcircuit instances just for testing.

See if the issue persists with native VSTs only.

Set “ThreadSchedulingModel” to 2 (if editable via INI/config)

In some older Cakewalk/SONAR versions, you could tweak thread scheduling via AUD.INI.

May not exist in Sonar 2025, but worth checking for advanced options.

Try Disabling Tempo Sync on Melda FX (if possible)

Just to test: if MTremolo or MRhythmizer has a non-tempo mode, see if the glitch is less severe. This would confirm the clock resync glitch as a root issue.

📬 When Reporting to Cakewalk Support:

Provide:

Repro steps: "Clicking on track number during playback in large project causes glitch."

Mention plugins involved (especially tempo-synced Melda FX and bridged Shortcircuit).

Attach project file (or a stripped-down repro version).

Link to the audio examples (like your rec1 and sine files).

Confirm that CbB 2019.09 did not have this issue under identical conditions.

🧩 Final Thoughts:

Unfortunately, this seems like a low-level timing bug or performance regression in Sonar 2025, likely affecting how UI thread interactions impact audio thread timing. It may be worse in larger projects or when bridged plugins are involved.

If it's a dealbreaker and you can't find a stable workaround, you might consider:

Keeping CbB around for critical mixing tasks

Using Reaper or another lightweight host just for playback and final bounces (many users offload this way)
https://audiobookcalcualtor.us/

[Wookiee]

@Jan have you considered it could be the FX in the FX bin in conjuction with the Pro Channel.  Have you tried it with the FX bin disabled and the PC enabled.

[Noel Borthwick]

On 7/10/2025 at 5:21 PM, Jan said:

I think I might have found the likely culprit - when the ProChannel is unchecked the glitch does NOT seem to occur. This would explain why it wasn't happening on MIDI tracks and when in "MIDI" view of Instrument track (they have no ProChannel to display). So I guess this is potentially a temporary fix for me, although that's still a bug and regression from 2019.09...

@Jan Can you share a simple project that exhibits this issue?

[Jan]

7 hours ago, Noel Borthwick said:

@Jan Can you share a simple project that exhibits this issue?

@Noel Borthwick as I said I wasn't particularly successful reproducing this in a blank project. I'll see if I can find one of mine that is "simple" (although I'm not entirely sure what would constitute a "simple" project?). Otherwise I suppose I can share the one where I first noticed that issue.

see post below

Edited 10 hours ago by Jan

[Jan]

7 hours ago, Noel Borthwick said:

@Jan Can you share a simple project that exhibits this issue?

@Noel Borthwick ok, I think I managed to get something for you. Here's a simple project containing a bunch of empty tracks, a bunch of copies of the metronome track (to give Sonar something to do) and a prerecorded sine wave track. I'm also attaching a recording (via MRecorder plugin) of me clicking on various tracks (32 sample buffer - see next paragraph) with the sine track soloed.

Since this project is not very CPU-demanding the issue is somewhaat reproducible under my usual 128 or 256 samples buffer although not very easily. Going up to 1024 on this sample project makes it completely unreproducible. However, I managed to get a 100% repro rate by setting the buffer to 32 samples. I also tested it under CbB 2019.09 and it can't be reproduced even on the smallest (16 samples) buffer possible. So clearly there's some CbB -> Sonar regression and given that it's project complexity/buffer size dependent it looks to be a CPU load issue related to the initializing/rendering of the mini-ProChannel view.

BTW on this project when NOT playing CbB 2019.09 shows 19% audio processing when under 32 samples. Sonar 2025.07 shows 23%.

One interesting discovery - in this case (mini-ProChannel view unchecked, but ProChannel displayed in its normal view) the issue does NOT occur.

But if you enable the mini-ProChannel view and still keep ProChannel displayed in its normal view the issue DOES return. So it must have something to do with rendering/initializing the mini-ProChannel view underneath.

I hope you'll find my root cause investigation useful.

glitch-project.zip glitch-2025_07_12 11_18_08.7z

Edited 10 hours ago by Jan
typos