Hi Billaw, Thanks for reporting in that error. I have reverted the FBX files and have uploaded a new build. I tested the new build in Unity 2019.3.15f1 and it reads correctly.
Please do try the FBX files in this new upload and leave a message here if it still does not work. If it still does not work - can you list the version of Unity, the 3d mesh format (FBX,OBJ,DAE, or C4D), and the image format (PNG, or TIF) you have used.