Booked on O fare, T-7 days to departure, viewing the seat map, and a "First Class +0 USD" seat shows on the selection page. When I attempt to select the seat, it says unavailable...kind of expected, but odd that the seat map is now showing for F.

In the past the F cabin has been X'ed out prior to upgrades (haven't received any notification), anyone have similar experiences? I'm a 75K, used a GGU for the outbound segment, so I wonder if seat selection tool can't handle a GGU leg outbound, then an economy leg inbound, and so it's showing seats in F for both flights.