I've imported an fbx object with 4 layers, 2 of which are designed for textures with alpha layers.
My issue is that that while the 2 first model layers (one layer with a corresponding layer for alpha) works perfectly fine, the two last layers does not allow me to paint directly on the model. Turning the brush size to "huge", it will sometimes paint on the model depending on the angle when brush wildly over the model, but the paint will not correspond to a natural place on the model.
Using the 2d view instead gives another issue. The texture fill layers seems to be shifted to the right, meaning I can't paint on the texture (with masks), instead I have to paint over the grey cover which shows no texture.
I've attached how my 2d view of the textures look for the layers