martinortiz (12/16/2023)
Another BIG issue is that when I import custom pants, if it is not conforming to figure, I will run collision on it...
It almost always tears the mesh....usually it will tear a zipper opening.
That's because the cloth mesh you imported is not solid to begin with.
It's already ripped, but you do not see it because vertices at the rip line occupy the same space.
First thing you do after the import, is go to Mesh > Edit Normals and run Auto smooth with Merge Identical Points checked.

This might not work if the distance between vertices at the rip line is beyond certain value.
In whch case you have to fix it at the source app, or export with appropriate settings to solidify the mesh on export (like from Marvelous designer).