UE5 can't read animation asset with bone names starting with number??

Development Character & Animation
,
1

20240207155713

I have bone names like this, and when .fbx is imported it doesn’t play.
Is this a sort of bug?

UE5.3 bone animation error - General / Feedback & Requests - Epic Developer Community Forums (unrealengine.com)

found this issue, maybe same problem?
It played fine in 4.21

please let me know if there is naming convention or what