Any issues with v20MR1 and APX SC-controlled hotspot?

Never set up a hotspot in the past, so not sure if I'm doing something wrong or if it's simply not working...

APX320 + XGS87 + SFOS 20.0-MR1 managed from Sophos Central. I go to my Guest SSID (not bridged, goes to VLAN) and turn on Hotspot. Client on the Guest network cannot reach the internet (web pages), and is NOT redirected to a hotspot landing page. However, I can see that DNS queries do get through to the Internet (Sophos DNS).

I have interactions/redirects set to the IP of the first port, in the Admin page. I have tried creating a rule to allow Guest-LAN traffic and it doesn't seem to help. I have Captive Portal on for both the Guest network/zone and the LAN network/zone

Turn off Hotspot and everything's back to normal.

Is there something else I'm missing? Should this be handled entirely within the APX, or does it depend on anything happening on the XGS? (Again, the AP is run from Sophos Central and no wireless control/options on the XGS side of things.