Generate Lightmap UVS Doesn't Update the Lightmap Coordinate Index

When importing an fbx file and using 'generate lightmap uvs', the light map coordinate index will not update correctly.

Working properly in 4.19 CL# 4033788

Found in 4.20 CL# 4212847 and 4.21 CL# 4221482

This is a regression.

1. Open the editor
2. Import an fbx with a material and texture
3. Check "generate lightmap uvs"
4. Open the StaticMesh
5. Expand the general settings

Results:
The lightmap coordinate index will be set to 0

Expected:
The lightmap coordinate index would be set to 1