Mark entire thread as read doesn't "bite"

[krilbe]

Using Owl (1.0.2) to connect to my employer's Microsoft 365 tenant. I have a serverside rule that moves certain messages to a subfolder. In that subfolder, when I mark entire thread as read, the entire thread is successfully marked as read and everything loooks alright. But if I click on some other folder and then click back to the subfolder where I makred a thread as read, then it will refetch the messages as being unread.

Actually viewing each message works. Manually clicking the "read" dot (switching it from green unread state to gray read state) on each message (without viewing them) also works. Marking the entire subfolder as read also works. As far as I can tell it is ONLY the command to mark a thread as read that has this problem.

I get the impression that Thunderbird marks them as read locally, but the operation is not propagated to the server, i.e. Owl doesn't pick up that this operation has been performed...?

Thunderbid 102.10.0 (64 bit) on Windows 11. No other extensions than Owl for Exchange.