Thumbnail section of Material Attributes does not function

The Thumbnail Tab in the Material Attributes does not effect the actual Content Browser Thumbnail Preview. The only way to current change it is edit it via the Edit Thumbnail Preview via the Content Browser

[Link Removed]

Also Reproduced in Main Promotable-CL-2455917

1. Open QAGame Editor
2. Open a Material
3. In the Material Attributes change the Thumbnail >> Primitive Type to TPT Cube from TBT_Sphere
4. Save and Close the Material

RESULTS: The Content Browser still shows a Sphere Primitive Type as the Thumbnail

EXPECTED: The Content Browser shows a Cube Primitive Type as the Thumbnail

Thumbnail Material Preview Mesh setting has no effect. Always sphere.