Undo & Redo Disabled - rotating objects trigger?

Hi, so this issue has been brought up already (here) and marked as solved, although I don't consider it solved at all, because having to reboot the software to unfreeze basic features is hardly ideal (and it brought up other issues such as this).

To recap: the Undo / Redo feature becomes unusable (greyed out) suddenly and there is no recourse except rebooting the software.

The weird thing is that I just noticed something and I think it's linked to the Undo / Redo freeze: sometimes an item will rotate a bit, apparently by the same amount (6 degrees) and apparently of its own accord. When I realise this I obviously think I touched something by mistake and try to UNDO, only to discover it's frozen again.

I know, super weird, but the two behaviours seem to be connected. This has happened to me several times over the last few days and it can't be a coincidence.

I'm on Big Sur, latest XD and using a Wacom Bamboo.