[HELP] Opacity maps + UDIMS

Hey all.

I am new to the program. I did this car (one single mesh, FBX) where I wanted to show the glass with some smudges but I cant get them to show with the opacity map.

The glass itself has color (albedo map) but I just wanted to show part of it with the opacity map but nothing shows (either shows everything by making the map less black, or nothing if its just B&W). The map is black and white as you can see on the picture. The textures come from Mari. Anyway I am not sure what I am doing wrong.

Thank you for your time.