I have a similar issue, so was searching the knowledge base for info about it and found this thread. For me, it even happens when I'm simply playing with input echo turned on between 2 external MIDI devices. Steps to reproduce: 1) Create a blank, new project. 2) Add a MIDI track. Set the input to MIDI Ch.1 (I have a Behringer U-Phoria UMC 1820, but also have had the issue using a Steinberg UR22). Set the output to the MIDI out. Turn input echo to "On" or "Auto Thru". I have a M-Audio Keystation-88 controller plugged in to the MIDI in, and a Yamaha MX61 plugged in to the MIDI out. 3) Start playing. I frequently find there are 1 or more keys that "stick" as if the sustain pedal is pressed only for that key. Right now, it's a low E. I can record a quick video if you don't believe me, but it's very strange. I don't even have to record to make this happen - just play with input echo. Interestingly, I just recorded, and it happens on playback as well. When I tried to redirect playback to a VST (just the default TTS-1), though, it didn't happen. So, the sustain is not in the recorded MIDI.