Hi!
Currently UE4 not support FBX 2016.
“…The UE4 FBX import pipeline uses FBX 2014. Using a different version during export may result in incompatibilities…”
Try to export into FBX2015/2014 or FBX2013.
Sometimes the FBX plugin does not correctly recognize complex hierarchy of the rig and bakes the animation with errors. Try to bake animation before exporting. You can use Bake Simulation command in MAYA.