Look up TS Tools, it’s solves a lot of these issues. Unreal has the worst FBX import work flow I have even seen.
The dialogue is messed up, Import all is not import all, not sure what it is to be honest.
Then pivots.
Don’t get Me started. We are moving from Unity to Unreal. I love the engine…but the FBX workfflow is terrible …Unity’s was near perfect. One FBX with separate objects with proper pivots. It’s one thing Unity gets right over Unreal.