Please start your tablet troubleshooting from the “3DCoat” framework that is called “TestStroke” for Windows:
https://pilgway.com/~sergyi/TestStroke/TestStroke.zip
This app is the first stop when narrowing pen-related problems. It contains all the system code without the “3DCoat” tools.
Note that Mouse mode is unsupported (Wacom Tablet Properties > Mapping tab > Mode should be Pen, not Mouse).
Make the strokes on your tablet and ensure the displayed strokes are correct. The strokes should depend on the pressure.
Press keys “1” and “2” to switch between “Wacom” and “WindowsInk” tablet interfaces. Note which of them is working for you.
Later, you will select between them in “3DCoat” using Edit > Preferences > Brushing > Tablet Interface.
After making sure that the “TestStroke” is working, rename the user data folder “Documents\3DCoat” into something like “–3DCoat”. This renaming is crucial because corrupted or incorrect “3DCoat” settings can lead to unlogical behavior of the “3DCoat”.
After renaming, run the “3DCoat”. It will create a new user data folder with default settings. Ensure the tablet works correctly, as in the “TestStroke”.
Switch in “3DCoat” preferences between “Wacom” and “WindowsInk” in case the “TestStroke” revealed that it was needed.
Manually restore your assets from the renamed user data folder into the newly created one.