Hi,
I tested your sbs in Designer 6.0.4 (the version you probably used to make your substance) and I don't have the same result as yours.
Here is mine with your sbs and without modifying aything.

By default your grunge map doesn't look like it should.
Did you test other grunge map ?
Can you send me your log file because here this is a issue with Designer, Painter displays what you should see in Designer.
You will find the log file in
Help ->
export log file Thanks !