Subscribe to Change Notifications as an Application for Online Meetings in GCC HIGH

Question

I have been having lots of issues trying to get my change notification subscription to work correctly.

Some context: This is an application I am attempting to write for my companies GCC High 365 that would track whenever someone enters or leaves a Teams meeting. To do this, I planned to use change notifications which seems to provide exactly what I want. As far as I can tell, this should be supported in GCC High as indicated in the beta subscription update page.

According to that page, I need to use the beta API and subscribe to the resource: /communications/onlineMeetings(joinWebUrl='{joinWebUrl}')/meetingCallEvents (with the web-url of the meeting filled in). This however, has never been successful. Graph responds with the error: Resource not found for the segment 'onlineMeetings'.

Interestingly, I found several examples online that claim to be monitoring change notifications, however they are using a different resource /communications/onlineMeetings/?$filter=JoinWebUrl eq '${meetingurl}' which interestingly is what is actually used in the beta subscription update page even though that conflicts with the other API page I found.

To further complicate things, this similarly fails if I try to use it on the beta branch as directed with the same error as before. Interestingly though, it succeeds if I use v1.0 -- hitting my notificationURL and providing a correct validation. Unfortunately, I receive no notifications regardless of what happens with the provided meeting. Additionally, the subscription appears to be created regardless of what URL I provide for the meetingurl.

Finally, I found this post on a Microsoft tech forum seemingly encountering the same issue but with no update from Microsoft.

So, what is the deal with this API -- does it not work in GCC High? Is it in the process of being updated from one format to another? How can I achieve what I am trying to accomplish?

Thanks.