The new process is really frustrating. Had a segment last week where I had been upgraded from exit row aisle to C+ middle in advance, only middles were available so I just went back to the seat map and selected my exit row aisle again.

Went to check in and all of a sudden I was kicked from my exit row aisle and placed in a standard Y aisle and C+ was showing as full despite 5 open seats showing on the upgrade page. Called in, nothing they could do about my exit row seat since it was now taken. Day of the flight, now 6 open seats were showing for C+ but only 2 people cleared into C+, both into aisles. Seat map still showed all the seats blacked out despite the upgrade list showing 6 available. Once boarded, multiple non-revs were brought forward to fill the remaining C+ seats.

Under 2 hour segment so not a big deal but pretty frustrating as I don't think anyone on earth would consider preferred exit row aisle to C+ middle an upgrade and switching back to that original seat apparently blocked me from selecting a C+ seat during check-in despite availability.