Ohh this is really strange ,  the question is now is the offset from the export or UE import.
You can try to import the whole animation into UE and cut it in parts with sequencer 

I guess I could probably just try cutting one of the existing ones into parts in UE5 and see if that does anything. Just need to work out how to cut things :)

EDITED: Just try the split in unreal and the joints stay in the correct positions between the transitions. 

Ok I think I've solved it. I think it's the 'rest motion root' in the preset settings (little cog) of Iclone's FBX exporter when unreal preset is chosen. If I untick it and import then the two animations match. Only issue I'm finding is it's seems to then more prone to crash Unreal when importing. 

Anyone know how to fix this with only CC and not Iclone? Well I'm not sure if its the same issue you guys have, but
the issue at least with the CC animation export is that the root motion is on the hip and all the bones, but not on the root bone itself, which is what UE likes.
I assumed the CC's "Sync Root and Hip Motion" option would have fixed that, but it didn't seem to do anything.
Does anyone know if the above mentioned option is maybe just not working properly?