Apple Classroom - Students able to deny call

We're a school using Apple School Manager, and have set up our classes through ASM. Our students are using school-owned 1-to-1 devices that remain on premises, and teachers use school-owned 1-to-1 devices but can take them off-campus.

At the beginning of the year, everything seemed to be working fine - teachers could view all the students in their Class and interact with them directly.

At some point in the last couple months, when the teachers attempt to view their class, the students will be listed as "Offline" until the teacher attempts to "Connect", which then rings on the student iPad, and gives the student an option to "Accept" or "Deny" - and this needs to be repeated every hour or so.

The student iPads, in the "Classroom" blade in the Settings app, also see options for "Remote Attendance Timeout" and "Remote Attendance Notification" - options which weren't there earlier in the year, and which one of our sister schools has confirmed do not appear for them.

We've confirmed that the teachers and students have Bluetooth turned on, are connected to the exact same Wireless AP, and are on the same vLan and subnet. Our firewall has access to all apple services (17.0.0.0/8) enabled for these devices, without any SSL inspection. Configurations are pushed out using JAMf Pro, if that has any bearing on the issue.

Can anyone shed light on why this has changed, what has actually changed, and what we can do to get it back to the way it was earlier in the year, where students are just automatically present in the class, without being prompted to "Allow" or "Deny"?

I've seen multiple posts here with similar issues, but none of them seem to have any actual information or solutions.