Help plz - Merge Actors with Forward Shading is Creating Funky Roughness Maps.

Hey all

I am using the forward shading renderer for vr. When I bake down material texture maps with the “merge actors” tool all the maps turn out fine except the roughness map. It turns out completely over the top shiny.

If I use the same maps in the deferred renderer it looks perfectly fine.

Any ideas as to why the roughness map looks way to shiney in the forward rederer?