Uuuurgh, such a pain hahahah. I’ve had worse problems with other engines though, Cryengine 3…released with 16bit floating point, Cryengine 2, 32bit floating point. I imported a Roman Colosseum model (with interior) into Cryengine 2, all looks great, put into Cryengine 3, everything is all skewed and vertices are merged due to the floating point values.
At the time, I had no idea, nor could find the reasoning for my mesh being messed up, I spend about 3 weeks trying to fix it before other people in the community had similar issues and a developer answered, lol.
Such is the nature of games engines.