Hi there - similar issue here.
Everything works alright with the mouse.
I’ve got the same problem - but it is related to the pen.
The cursor disappears when I hover over the tablet with the pen.
I can’t draw properly as I don’t see where the pen is actually going - but it does draw if it touches the tablet.
Does not happen with GIMP. I can see the pen hovering.
Device is a Waltop Slim 12.1" tablet. (ID 172f:0034).
Ubuntu is 16.04 LTS, stock drivers out of the box.
This started when doing a new clean install for Ubuntu.
It was working properly with Ubuntu 14.04 LTS and MyPaint of that version.
Any ideas of how to circumvent this?