Cloth Physics Clipping I'm trying to make a shirt to go on my model. However when adding cloth physics, for half of the model the shirt collides into the model for a small amount of time before clipping through.
I created these two sheets to show basically what the shirt is doing when running the simulation.

The model other then the hair is one whole object with the collision modifier, with the other side of the model being exactly the same, just reversed with no mirror modifier. I tried importing this into the 2.79b version of blender and I don't get this issue at all. Any idea of why this would happen? This issue is occurring in blender version 2.91
This looks to be a problem with Normals - with the Normals at one side of your model pointing ‘outwards’ and the other side ‘inwards’. Did you model by mirroring the opposite side?
Check and correct your normals (might be able to just ‘recalculate normals’ or select the problem areas and ‘flip normals’) and re-run your simulation.