I'm on the upgrade waitlist for AC881 this Sunday. When I do a dummy booking on AC.com it will allow me to "buy" two seats, which normally tells me that two seats are available for sale. But when I look at the seat map, it shows all J seats as occupied.

I'm used to seeing the reverse where there are more seats available on the seatmap than for sale, but I'm trying to understand what this means - is this an indication that there are some staff currently seated in J that AC will bump back if they actually sell their seats or is there some other explanation?