I’ve bumped into this every now and then, sometimes when I open Renoise, the keyboard looks like this
and only the white keys work as they should, the darker ones are pressed down and they play the sound, but they are pressed for like 2 seconds and only after that they get unpressed.
If I restart Renoise, it works correctly. Latest version, w11
Looking at the image it simply looks like there is a scale set, so it highlights (and makes you play) only the notes in the scale. but from what I understand from the description it seems to me that the problem is not exactly this.
Do you have any midi controllers etc. setup?
I agree with Dr4am that it looks like a scale has been selected in the instrument settings:
This is controlled by CC’s 14 and 15, so if you’re bumping any knobs on a controller set to those CC#'s, and you have the device set up to be recorded in your preferences, then it’ll bonk your instrument into a scale (it looks like a whole tone scale to me).
If this is what’s happening for you, you can turn off recording of CC’s and program changes (if you don’t need them) in your Midi preferences. Or at least that’s what I do 
Edit: I missed the second issue in your post. You might also have something that’s bumping CC 9, which is the quantize setting, and this could be responsible for the black keys having the behavior your describe. The fact that it’s different between white and black keys is weird though – I’m very curious to see what you find!
I have an Akai MPK61 midi keyboard connected, I will have to check if the scale is set next time I get this, though it might take a month for the next time. I don’t touch the keyboard at all when I start Renoise, so unless it’s somehow sending some sort of ghost messages, then I don’t know what’s causing it.
If the scale is set, shouldn’t the darkened keys be unplayable? Sometimes those keys don’t make any sound, but yesterday when I once again got this, everything worked normally otherwise, except when I pressed a darkened key, the sound did play but it took 2 seconds for they key to be unpressed, and while it was down, no other keys worked, so it kind of feels like it stole all resources for itself or created a huge lag
Also, this never happens in the middle of using Renoise, the issue is or isn’t there when Renoise has just been started, and restarting Renoise fixes it always
The sure thing is that off-scale buttons are not silent, but play nearby notes in scale. For example with the C Phrygian scale, pressing X is = S, yes it’s possible that it’s a lot of latency and I don’t know what other problem…
