>>277283743
Look at this super high quality VR post, very cool.
>>277282734
Usually it occurs when your head height is too short and the bones in your armature fold in on themselves, try placing your head/viewpoint as close to the models actual one as possible when calibrating in on fbt. 
Another reason this could be happening is rotation/positioning might be off on the actual bone and the simplest way is to just run it through CATS fbt fix.