I occasionally have this as well, often by the same prop maker. Almost all of his props are fine, but every once in a while a few have this problem.
If i come across one, I send him a message and get a correct one back and usually he updates the package at the store.
If i remember correctly it needed a simple operation such as Normalize UVMap (or coordinates).
Configuration: Windows 10 64bit Creators Edition, I7 6850K, 128GB, 2 GeForce 1080ti, P11 Pro SR6