Last week was on SAN-SJC E175 and also there were more F seats available than elites to be upgraded. At the gate there was an announcement offering a paid upgrade into F. No idea if anyone took it up.

BTW 4 seats in the back of F were blocked on the seatmap and remained empty, no idea why. Same 4 seats were blocked in the incoming flight (same plane). The flight went out with maybe 1 or 2 empty Y seats so there was no need to upgrade more pax to F.