it's because maybe you have not enabled certain things in the exporter like 'keep vertex order' always make sure you have exported the correct subdivision level as well. when posting its best to mention which software you are using too :) though i guessed it was zbrushI generally use xnormal for baking anyway
Two quick things you can try: A: delete your morph target and see if it exports right. Or B: turn on "switch MT" in the options and see it that works. If those don't work, similar to what Ruz suggested: is the point count the same when you switch between apps? Are you modifying the topology in max at all (adding modifiers…
Well, after hours of suffering, it turned out that everything works out if you split such problem mesh on polygroups corresponding to UDIMs and bake them separetly. Wierd and time consuming. Left this note just in case anyone run into this issue again.
Hmm...that's strange. I was going to suggest to just try the multi map exporter on your original sculpt (without editing the mesh externally) just as a test to see if that works correctly, and if so, then you'll know it's some kind of issue with transferring the mesh back and forth between apps. Doubly strange regarding…
The truth is out there somewhere. I guess you are right about transfering issue. Probably something went wrong-the project contains a lot of subtools exported from the same Max scene, and this problem appeared only with some of them (including original version). Others baked fine even in cases when mesh had UVs on…