I use MotionBuilder for all of our player animations and would up to 4.9 export takes as individual files and batch import into UE4 with no problems.
In 4.10 I can import the rigged mesh just fine but when importing a animation take assigned to the rig it just sits there trying to parse the file and then at some point crashes.
I’ve test the files using the same process using 4.9 and it all works fine as well I re-downloaded and installed a fresh version but sill no go.