Incorrect lightmap UVs

Pulling my hair out on this. Original Maya FBX imported with auto generate Lightmap UV checked.

However on inspection of some individual meshes noticing HUGE issues with missing, broken and overlapping Lightmap UVs.
The attached is one example. My texture UV looks perfect.
But even after applying changes cannot get something that looks usable for my Lightmap UVs.

(channel 1)

settings.JPG