This is a serious issue. I mention something similar in the thread Record CV dropping gates when unquantized and UI glitches In my case the midi controller was plugged to the “USB device input” and I noticed that Hermod was sending a duplicate Note On instead of a Note on - Note off pair. Do you have the possibility to route a “Midi out” to a computer and check with “Midi Monitor” if that’s also the case in your setup ?