I’m getting those type of issues even by staying inside UE5.6 with MH from UE5.5. basically just by modifying the MH from UE5.5 to UE5.6. I got that weird body like yours.
While creating the new modified MH I got a message that it would affect all my MH in Bridge and fro. UE5.5. After hours of work I could not do anything else than accept. Well… Now all my imported MH from UE5.5 are broken like that.
Hopefully they will fix this bug Pronto!