Hi, I was also experiencing the same issue. I am using an Xp Pen tablet that is the Deco Mini 7. In another post, I mentioned that when I tried to click on the menu options at the top of the program with the tablet, the drop down options did not appear like they should. However, when I used the touchpad, the menu options worked fine. I used the tablet before on the previous version of Animation Paper and the menu options worked fine, but with Alpha 8.1 they did not.
I recently reinstalled the program to see if anything changed but it still does not work properly.