Hi 3dtrialpractice !

XRAY view is intended for use with joints/skeleton/bones within a rig/model, if none are there, then nothing will be shown.

As a quick test, we created a cube with a bone that stretches through the top and bottom of the cube in MotionBuilder, and then exported as FBX, I then opened the FBX in quicktime and cycled through the “v” function with the information window = on and I am seeing the expected results

Models Only = only seeing the geometry
Normal = I can only see the portions of the bone that protrude beyond the cube
XRAY = I can see all of the bone whether it is inside or extending beyond the cube

If this is not what you are seeing, then I would ask you to attach a file along with details such as which version of MotionBuilder ( or other app ) and which version of the FBX plugin you’re using so that we can see what’s going on

I hope this helps !
- Damon