Yes, I'm working on XKT patch.
Well, I've copied the three folders of surfaces to the TE4 folder and I've loaded the default profile, the only modification are these three folders, and the line still appears.
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EDIT: Good news, I've solved the problem, I'll try to explain how in case anyone has the same problem. If you take an image and replace it, the line appears, but if you modify that image by removing half of it and duplicating the remaining half and inverting it horizontally, the line disappears... I don't know if I explained it correctly...