One hypothesis; your AP's are close enough to each other than your clients are still connected to a single AP vs roaming to the nearest, because of signal overlap (and your AP's are broadcasting at higher transmit levels). When you brought everything back on line, all of your devices attached to the first AP they saw, and the signal was strong enough there was no reason to roam to a different AP.
In a multi AP environment (Cisco, Aruba or Meraki I'm familar with) the controller will turn down the power on the AP's automatically if they detect each other, minimizing the overlap.
Also, I have a similar setup at the house (just under 4000 sq, including the garage, all Meraki gear) with 4 access points (one upstairs, one at south end of home, one north end, and the last in the garage). What I did on the 2.4 side only the three first floor AP's are broadcasting.(Channels 1, 6 and 11). On the 5GHz side, I spaced the channels far enough from each other to eliminate the overlap, then further reduced the power on each. By doing those two things, I'm forcing a device on the 2.4 side to attach to one of the 3 AP's--pick one, any one, but only one of the three. On the 5GHz side, I turned down the power enough that a device on our first floor will barely connect, if at all, to the AP on the second floor.