Promidi

What is your MIDI driver mode (MME / UWP)...... have you tried changing it? (Do this with no projects open) Preferences - MIDI - Playback and Recording

Definitely not normal behaviour. (I have never experienced this with any version of Sonar or Cakewalk) What keyboard is this? Are you using the latest drivers for your keyboard. Is everything else up to date. What OS?

My normal view of the controller lane in the PRV is with "Show Multiple Lanes" disabled. If you have multiple controllers on a track, the Key/Pitch part of the pane lists the controllers you can click to display that particular controller's data. If would be handy if you could hold down a modifier key (Like SHIFT, CTRL or ALT) while clicking on another controller to add that controller's data to the controller lane. For instance I might have many controllers in a given track, but I only want to display the lane for Volume (CC7) and Pan (CC10). While I know I could just select "Show Multiple Lanes", I sometimes use up to 20+ controllers per track, so enabling this would make the controllers uneditable. I would only really need a few visible at one time.

When you say "The dll file is in a proper VST folder", can you confirm that it is in a folder that you know that CbB scans. Also, have to gone into CbB preferences | Files | VST settings and performed a reset and scan (in that order). Maybe enable "Scan in sandbox" and see of that makes a difference.

There is a transform tool on the PRV where you can adjust the contours of consecutive controller events and velocities to follow the general shape of a bounding rectangle. It would be great if we had a similar tool to change the curves of automation nodes.

What OS are you using. Is your OS fully patched? What USB to MIDI interface are you using? Are you using the latest driver for it. Are you using a USB port directly on your PC and not a USB hub. If using Windows 10, have you tried different MIDI modes (MINE and UWP)? Also, on a MIDI project , select all and then use event list to make sure there are no stray events therein. Do your start notes and events start bang on 1:0:0 or do you have a "lead-in" measure before the events start. Does your project initialise patches for each track? - some MIDI hardware needs time to respond to these patches before sending other events. Do you have any initialisation strings set as sysex data.

Have you made sure that power management for your USB root hubs is disabled

I don't update from within BA anynore. I just download and install it manually (with BA exited of course)

Works fine here with the latest Cakewalk by Bandlab