Viewport Canvas paint on object problems

[0SMF0]

I've been using the viewport canvas for some weathering and usage texture painting to much success but I've come accross a problem recently on a certain object but no other. The object in question has been unwrapped with full UV co-ordinates. The brush is showing up in 2d view where I can paint successfuly, it will then update in the viewport on the object; BUT the brush is not showing up in the viewport on the object and WILL update back in the 2d view.

Side note; when I re-opened the file the gamma/lut option came up which puzzled me because it was already set.

Have I accidently knocked a keyboard short cut or something?

Any light on this would be great.

Thanks.

[ekahennequet]

I can't tell what's going on without looking at the scene and can't duplicate this problem.  Could it be that the object has flipped normals and that you're not seeing it being painted? Try applying the Normal modifier and check "Flip Normals" and see if that makes a difference.