If it looks like nothing is happening, check that the normals are pointing in de right direction.
Happened to me 
viewport overlays → face orientation
Hope this helps
Br Tommy
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Always good to check normals when trouble shooting. Good advice
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Still nothing happening when I try and paint with the Texture Mask.
Further testing. It’s only the base which I can’t paint.
Have successfully texture-mask painted other parts of the tower.
Will update for others reference if I fix it.
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So I was having this issue as well and my normals were good, but I may have solved it.
Directly above the Texture Mask options is the Texture options. That was set to a black texture for me. Removing this black texture (but leaving the clouds Texture Mask) allowed me to finally paint.
Hope this helps!
1 Like