Recently I purchased a Huion H320M. It works well, however if I enable "Mouse Mode" then the pen's Buttons 2/3 stop working correctly. I need these buttons to work properly, I'm a 3D Artist who works mainly in Autodesk Maya and Substance Painter, so binding the pen's buttons 2/3 to "Middle Mouse" and "Right Mouse" are absolutely necessary for my workflow. But they don't work if I enable "Mouse Mode", only if this functionality is disabled.
I recorded a video of the problem here: https://www.youtube.com/watch?v=1sZpaYTvMjM
Is there anything else I can try besides trying new/old drivers and unplugging the device? Nothing seems to work.