Also make sure they are -properly- UV mapped. My personal problem was, a face had its UV map as a single line instead of square. When I fixed that the problem was gone.
At the moment 4.7 literally breaks everything of the mapping if it sees a single error. Before that the uv mapping still worked even you had bad uv mapping so you probably didn’t realise. This is fixed at 4.8 but you still need to check where you are making the mistake.