Export to the new set of mannequin bones which has unreal 5.

The unreal 5 mannequin and metahumans have a new bone structure and all the examples released by unreal (Lyra, Mannequins Pack, etc) use that new system.
https://www.unrealengine.com/marketplace/en-US/product/mannequins-asset-pack?sessionInvalidated=true
https://www.unrealengine.com/marketplace/en-US/product/lyra


You can vote here:
https://www.reallusion.com/FeedBackTracker/Issue/Export-to-the-new-set-of-mannequin-bones-which-has-unreal-5