Just FYI - Geofence is still not working on my wife's pixel.
I've been testing it here and have been 3/3 in having the geofence trigger both exit and return on the new beta. You updated your wife to the beta or just the AT&T cheap phones?
I have noticed that the initial geofence trigger, when going from the phone being stationary (relative to GPS I mean) to moving can be significantly delayed. Like minutes later. But Google basically says this is a feature and so live with it. They are annoyingly become more and more like Apple in the background usage realm.