Try GeoDav’s answer here:
https://.unrealengine.com/showthread.php?18094-Import-Skeletal-Mesh
my guess is that you have exported the character and imported a modified version, the problem is that when you export a skel mesh from UE4 it adds an extra root bone (standard for fbx api) there’s a good chance that this “root” bone is named the same as the mesh, so you need to delete it before you export from your 3d program, the lowest bone name should be b_root , that is if you are using the Epic content
I also found this:
When exporting HeroTPP.fbx from Unreal, for some reason, a dummy node called HeroTPP is also added to the bones system when you open it in 3D Max. If you delete that HeroTPP dummy helper, everything works like a charm!