Issue still occurring with using Vanilla SPA 5.1 and UE5 Mannequin Pack
I set up the UE5 Manny Skeleton VB and Sockets to match SPA UE4 Skeleton FullBody 1 & 2. I setup IKRigs & IKRetargeter for UE4-to-UE5 in the same way I have for other animations that work with no issues.
Please advise the method and steps you are using so I can duplicate your success.