A FlyerTalk Posting Legend
Join Date: Sep 2012
Location: SFO
Programs: AC SE MM, BA Gold, SQ Silver, Bonvoy Tit LTG, Hyatt Glob, HH Diamond
Posts: 44,338
That seems easy. "This isn't an AC lounge".
I've never seen that, but I have had confusing lounge interactions. Mostly related to arrival lounges, where access requirements are not exactly clear.
I don't know how they could make it more clear than "AC MLL". Those don't exist in DUB.
But I know the lounge you're thinking of. It was easy for me, but I was AC*G in LH J. They even slowed me down to ask if I had a guest.