And yet on my other 2 domestic BP's (ACE-MAD and VLC-MAD), I am Group 1 and Group 3 respectively. Even weirder, on the first 2 BP's there's no status but on the VLC one, where I'm Group 3, it does actually say Emerald.

Also - so does only the person on the booking with status get priority check in, boarding, etc, with IB? (And therefore non-status companions are expected to check in their cabin bags). Seat selection seems to extend to all pax IME so far.