Drobo 5N2 802.3ad setup with Ubiquiti switch/router?

I was pleased to see that 802.3ad link aggregation support was added in release 4.2.2. This change doesn’t seem to have made it to the documentation. I tried doing the obvious thing, selecting 802.3ad on the Drobo, and configuring the ports on the switch (a Unifi Switch PRO 24) as a Link Aggregation Group, but as soon as I enable LAG on the switch, the Drobo becomes inaccessible. If I enable 802.3ad on the Drobo but no link aggregation on the switch, I can talk to the Drobo normally, but I’m not convinced that there’s actually any aggregation happening at all.

Suggestions, insights?

Did you ever get this set up?