I’m sorry, it could be anything from the system. The OS, the graphic card, the driver of the graphic card, the screen resolution, The screens layout, the HiDPI mode + settings, the Preferences, the 3rd party software (especially the one, which changes the graphic), timing issues…
I also haven’t seen this report here on the forum since your report. So I don’t think it’s a generic issue. I believe, if everyone would meet this issue, the forum would be full of it. But I always try to reproduce it, to get at least a picture, if it might be generic issue or not. If I can’t reproduce it straight away, I try to get closer… To use the exactly same project (it might be, something is buggy in the specific combination of… I don’t know, the MIDI Notes and the CCs you are using, whatever…). If this doesn’t help and my intuition says, it could be in the preferences, I try to ask for the preferences folder.
So my way is to try to reproduce it on my system and to find out, what really causes the issue. But it doesn’t work without the users help.