HP OfficeJet 7612 on Ubiquiti UAP-AC Lite

Protip: The HP OfficeJet 7612 (at least with what is claimed to be the most recent [2018/03/24] firmware) does not support Ubiquiti's implementation of Fast Roaming, 802.11r-2008. The UAPs are running f/w 3.9.21.8191. We made this obversvation after downgrading the UAPs to an ancient 3.4.x firmware version. Fast Roaming didn't show up until 3.7.x, that was the clue. Just in case anyone else runs into a similar issue... All of our other devices, including the cheap wireless cameras, have no issue with Fast Roaming. I'm placing the blame for this squarely on HP's firmware.