When you open the same appointment in the Bookings calendar (not Outlook), do you see the 3 answers there?
Yes - I see them in Bookings. I have no idea if my teachers can because I'm the one who created the shared Bookings
Is the service set to 1:1 (one parent per time slot), or can more than one parent book the same time slot (group/multi‑attendee)? If it is group/multi‑attendee, Outlook may show a more “generic” event and not show the custom answers.
The service is set to 1:1. I've done this process successfully for 3 years and suddenly it doesn't work NOW.
Are the teachers added as Staff in Bookings, and are they assigned to this service?
Yes. I create a service within the Bookings for each department, add staff, and assigned them to this service.
Which Outlook app are teachers using (Outlook on the web, Outlook for Windows, or mobile), and is it missing in all of them?
To be fair, I only use Outlook on the web and did not test with Outlook for Windows. I just checked on the Mobile and it also doesn't provide the information.