Sorry I have had no further time to look into this. Hopefully in the next few weeks. My issue was with R20. It was an obj from the Moana dataset. I expect the polygon indices to match up with the same values within the ptex files, but it doesn't look like they do. I will need to investigate further to determine if it is the OBJ loader or not. But since people have indicated issues before that does fit with what I am experiencing. The OBJ file format has many different paths regarding how it could be loaded and interpreted. So it doesn't surprise me if one of these paths doesn't respect the polygon order.