I have a Huion Inspiroy H640P tablet and pen and I am having the following problem.
When I try and use this in the Affinity Photo for Windows 10 I can see the pen move, I can select a menu item, move layers etc.
However, when I try and use the brush option it will not paint. I can see the brush move, change size, hardness etc. But it will not put down any colour.
I have tested that I am on the correct layer and not using the undo brush, by trying the pen, then put down the pen and without making any other changes I then use the mouse/trackpad, and they work fine.