I know a similar topic was recently covered ad nauseam but this seems different than what I was experiencing AND I just spent too much time looking for it so forgive the dupe if it is... And, thank you in advance for those who will point out my ignorance and lack of search ability.

I have ATLMSP booked for tomorrow in Comfort + and the app and website keep offering to up sell me to 1st for far too much money to even consider. However, when looking at seat map, there are none showing available. Separately, I went to see what might be available (any cabin) on earlier flights for same day change. I noticed they were still selling 1st class seats on my flight so I checked the map and 2 seats were showing available.

In the previous thread, it seemed they "fixed" or changed the part about not being able to see available seats in other cabins so I find this curious.