Was I not clear in expressing the problem or or it affects my use of Thunderbird? I posted this problem over two weeks ago, but it appears no one else is concerned.

My PC is an MS Windows compatible desktop running Windows 10 20H2. I am using Thunderbird V91.4.0 (32 bit)

I have several folders in my main email account in Thunderbird that are automatically populated by the use of multiple filters such that the source of the messages and/or the content are segregated from the main inbox. For many years now when getting messages an alert would popup from the system tray listing the total count of messages and a summary of most of them. Upon applying a recent update to Thunderbird a few days ago, this alert only showed the count for the inbox and, although they were properly filtered, none of the messages for other than the inbox were shown in the alert list. The failure to list the total received count leaves me in the dark as to how many were received other than in the inbox.

The latest TB update (91.4.1 32bit) seems to solve most of the problem. The popup list is a little different and shows only one message although the count is correct. Thanks for that!