I am having the same problem, in my case I work in max and the checks of max, as well as mine and the reviewers, is that there is no overlapping, but still I have thrown the work back many times because of this problem. Fortunately, when I send them several times a writing and images to prove that there is no overlapping, they end up checking it themselves instead of just looking at the error that comes out in the verification program. I have also done many tests and the problem persists, so I guess it is because the verification program does not like some kind of shape in the islands. Separate pieces, separate the islands by a lot of space, redo the uv several times, redo the textures, nothing works. If someone can find the solution, please share it, so they will stop throwing our work back.
I am having the same problem too, ı tried everything but ı don't know what ı have to do.
