Are you still working on that bug because i'm still getting this error now and then with no way to fix it so far. Only thing that helps for me is setting up a completely new file
When baking AO using multiple texture sets, objects that are using one texture set aren't affecting AO on objects using another texture sets as if "Ignore groups" were unchecked. I created a simple scene to demonstrate the bug. 1. First object using texture set #1 2. Second object using texture set #2 As you can see AO…