Hallelujah!!!
Ok. So I’m in the functional club with 632 and UniFi non-mesh access points.
Mine worked for months, then dreaded no response in HomeKit yet fully functional in rachio app.
Was digging through this thread and tested a new UniFi feature, not sure when it showed up, and when I clicked manually add accessory in HomeKit it actually showed up in HomeKit! Entered my pin and boom!
In UniFi controller v6.2.26
Settings>wifi>Select wifi name(mine is a shared 5/2.4)>edit>advanced>Optimize IOT wifi connectivity
I turned this on for both. It reprovisioned the AP’s and instantly worked.
IF your on UniFi. Give it a try.