BC7 Format in Texture Asset Mip Maps are not correct

When enabling BC7 compression format for a texture in a project that has SM4 disabled will result in the last two Mip Levels being gray. This happens on any texture size. The number o mip levels may differ but it will be the last two levels that are gray.

For a resolution of 64x64 there will be 6 mips and with the final two being gray. For a 2048 texture there will be 11 mips with 10 &11 both being gray.

1. In the Project Settings > Supported Platforms > Disable all EXCEPT Windows
2. In Project Settings > Platforms > Windows > Disable DIRECTX (SM4)
3. Restart the Editor
4. With any texture, You can use Engine Content (I used AICON-Green)
5. Change the Compression Settings to BC7.
6. Enable the option in the top toolbar for Mip Level, and change the Mip Level incrementally until it turns gray.

Regression: No

Results: The last two Mip Levels turn Gray for any texture size. The number of mip levels may differ but it's always the last two that turn gray.

Expected: Last two mip levels should have a similar color to the base color of the texture.