Automatic Weights doesn't work well on a cloth simulation mesh, but works perfectly on a handmade one

Question

I have created a mesh using a cloth simulation and sewing, after I applied it, I merged all sewing points and applied an armature deform using the auto weights. It works badly, like this:

After trying everything I decided to try the auto weights with this armature with increasingly more complex meshes until I ended up replicating the mesh manually (magnet + extrude + F) so that I have the exact same mesh, and I applied the auto weighting, and now, it works much better:

Both meshes are the exact same and still, the auto weights work badly on the first one: why does this happen? Is there some king of atribute in the original object which is disrupting the auto weights system?

Thank you for your help!

Answer 1

Ok, so if someone is in the same situation as me, I found a way to make the Automatic Weights work: you must apply a remesh or some kind of modifier which will change the mesh, for example: I applied a wireframe with very low thickness, merged all verts automatically with Auto Merge, rebuilt all faces with Mesh - Clean Up- Fill Holes; and now it works perfectly. So now you end up with exactly the same mesh, but the Auto Weights will work.

Probably there is a much simpler and sophisticated way to do this, but this way works.