Yesterday i started Renoise - latest version downloaded yesterday from backstage to test my Yamaha CS6R.
Setup was like:
Master keyboard selected as midi in in preferences then i set up midi output for first instrument.
When i was playing notes on my keyboard note off messages were send just after note on, it didnt happen when i was playing chords (but still got note offs from time to time).
My keyboard, midi interface, that Yamaha works perfect - i did the same in Ableton Live few minutes later and was ok.
I started fresh install of Renoise and just changed midi in and set midi out on instrument. I didnt record anything, just played around.
That happened regardless the speed of playing.
I can test more in the evening.
I see. Please when you test this again pay attention to the green and the red midi indicator on top right in Renoise.
That might tell you where those note-off’s originate from.
Another possibility is that you have used the duration slider in midi properties for that instrument.
If it is not set to infinity then renoise will send note-off’s…