Input from a friend of mine who knows Nuke very well:
deltadave
4 hours ago
Does UE4 allow import of alembic files? Perhaps that
would be another option, if fbx doesn’t work. The
other possibility is that UE4 reads the axis in
different order than nuke outputs. Try using zyx
rather than xyz (which is the nuke default, IIRC).
If the camera is just rotated 90 degrees, offset
it in nuke by 90 using the camera tracker
(same link as above).
Here is one of the shots I tracked in Nuke:
