This is not a big deal, no work is lost and a reboot of the mac solves the problem.
But it is weird.
Every so often in Painter 12, the Wacom cursor dies. The Mac cursors work and P-12 works (with a mouse) so I can save and close P-12 and reboot the Mac.
Just closing and opening P-12 is not enough, the Mac must be cycled.
After the Mac is up, the Wacom cursor is initially sluggish (like the settings are gone), but quickly everything is back to normal.
No P-12 data is lost, the Wacom tablet and pen custom settings are intact and life is good.
Do not know what triggers it, can't reproduce it