the new cloth physics are great but when I have a cape and use ragdoll they seem to freak out. here are 2 meshes imported the same way just one with the cape when I click simulate in persona one ragdolls fine and the one with the cape goes bananas!
I got the same problem for a long time now (UE 4.17)
don’t know how to fix it but you can check my post maybe it helps you a little bit:
if you solve this problem somehow, please let me know 