Random brush/color switching

I am using Windows 10
a Huion H610 V2 tablet - all drivers current
Painter 2019 - all drivers current

Problem: When using the tablet, the brushes will randomly switch to previously used brushes. The colors will also randomly switch to previously used colors.

This does not happen using the mouse
I am not accidentally pressing the button on the pen
It does not happen using the tablet in any other program
It does not happen when using the tablet in other Corel programs

I have rebooted
deleted and reinstalled drivers for both Painter and the Huion tablet
I restored Painter to factory defaults
I restored all workspaces
I turned off the Painter option to show previously used brushes

Further details:
If I wave the pen over the tablet it will sometimes switch back the brush or the color - but that's random too. I usually have to reselect.

Can anyone help?
Thank you!