The rulebook for the app covers this. It only shows one location for any sort of monster groups, which is effectively what you've got in this example. You put the Master version on that point, and put the rest on the closest available locations.
So I guess, 1) I agree, 2) Not a bug, 3) Separate monster groups.
I guess I'm agreeing entirely with Tatsu.
You are right about the rule book. I didn't even equate this with the visual cues used to place monsters normally. And I have played 3 campaigns. Duh! Thanks!