Have a bit of an oddball issue:

I'm a few days out currently from my trip, and despite there being many non-preferred window seats open on the seat map, they're not open for the $29 purchase online. Middle and aisle seats are, roughly matching the seat map (I didn't compare every row, but a quick comparison seems to line up.) This was booked as a basic economy award ticket.

First, any ideas why this may be happening? Secondly, if I check in right at T-24 will those window seats open up if available on the general seat map, or would I still be blocked out from selecting those?