I'm running Windows 10 and recently switched from the ESR Channel version (128.11.1) to the Release Channel version (139.0.2) and, since then, have started having a problem where the unread email count displayed on the system tray icon and also the count on the Taskbar icon are no longer correct. Most incoming, unread emails aren't counted. This feature has always worked correctly for me previously, ever since I first installed Thunderbird several years ago. When I go into Thunderbird, the count of unread emails in whatever folder they're in is still correct, the problem is just with the counts on the taskbar and tray icons.

I'm not 100% sure, but I *think* it might be the case that emails which end up in the default "Inbox" folder are added to the counts, but those which are automatically allocated on arrival to other folders on the basis of filter rules aren't being added to the counts displayed on the icons. I have searched for others reporting the same issue and haven't been able to find anything, so it seems unlikely that it's a bug. I'd greatly appreciate any help in resolving this issue please.