Hi! Did you find any information online on what could cause the problems? This would help me to see if there's something I could do without making a custom collider for each object in Blender
I tried Unreal Engine and UEFN using convex decomposition on both, and I tried to find other solutions, but the only way is to redo the collisions to get some that really stick to the object. (Especially for the larger ones).
This isn't a problem that comes only from your pack, but from almost all Unity assets imported into UEFN.