Started recently, but I cant be sure when. [Im on Unstable]
Every time cursor comes within a dozen pixels or so to the top of the screen the pointer goes missing.
If you have a top panel and are less than careful this almost presents as ‘when entering panel’.
It is always still functional, just not visible.
It may recover almost instantly, after movement, or stay shy for a small amount of time/area.
This has never been fatal, just more of an annoyance.
Possibly the same as here:
Given the other report this very well could be amdgpu related.
Edit - Yes, to be clear this only occurs on 4.20. Only checked 4.19, but it is unaffected.