I have encountered this behavior before, but it isn’t really reproducible. Sometimes when booting up Renoise, holding down a key on the computer keyboard wont enter in the note-events or values in the pattern editor while in edit mode for the duration you’re holding down the key. It will only enter one event and stop. It doesn’t seem to matter in what track, column of the track you’re in.
Minimizing Renoise and bringing it back up seems to fix this behavior, bringing back the repeat functionality.
(Windows 10, keyboard repeat rate in preferences Keys tab set to 5 ms, Gui scaling is set to 125%, limit frame rate to 60fps).