Unable to subscribe to Office 365 IMAP folders from MUA since 2022-11-01

Just to confirm, the issue is not just with Thunderbird, but also with Gnome evolution,

with the error message: Error fetching subscribed folders: LSUB failed.

So it seems to be definitely not the MUA.

I get the same error (LSUB failed) using Vivaldi Mail. Whether I log in using a password or OAuth does not make any difference. I am not the only one having the issue, see https://forum.vivaldi.net/topic/80723/lsub-failed-with-office-365-imap-server

Nor me either.

I'm having the exact same issue for accounts on my tenant. In my case, deleting an affected O365 account from TB and re-adding it resulted in the fault returning. I took that same account and added it to a separate test machine with a fresh install of TB on it, and got the same fault again.

Ergo - this fault is staying with the affected account(s), and not the device accessing it. The identical TB (Oauth2) config has been used throughout my testing as evidenced by the fact that I can send and receive quite happily on an affected account, and I can see the folders if I set TB to display all folders regardless of subscription.

What I did find is if I added some test accounts from my tenant that hadn't been accessed via IMAP before, that actually worked perfectly well including the subscription functionality. I now have three such accounts which have been working OK for several days now.

So it appears that something has happened that has broken JUST the IMAP subscription functionality, and on accounts that were using IMAP at the time the problem occurred.

Before anyone mentions deprecation of basic auth, the affected accounts were reconfigured to Oauth2 months ago in preparation for that change, and everything worked fine until the other day.

I have tried turning off IMAP on an affected account in Admin Centre, then turning it back on, and that had no effect.

I have my account setup in Tbird w/IMAP (have for years) on serveral systems, and same thing, though it started a week ago on one laptop, hit the other a couple days later, then finally my desktop yesterday. Inbox and Deleted are the only folders displayed no matter what I try.

I'm having the same problem with 2 out of 3 email accounts. All three accounts are the same domain. One of them works with subscribe to folders under Thunderbird and the other two don't. I've tried these with Thunderbird on Linux and Windows PCs and in every case the one account works as expected and the other two don't I've attempted to find something different in the accounts but with the visibility I have can't find anything. All three accounts were working properly until around the 1st of November. I actually had one of the folders open and looking at the contents when it just evaporated before my eyes.