UPDATE TO ABOVE: I now have version 115.4.1 and Unified Folders still does not work. The reason I have Thunderbird is BECAUSE of the Unified Folders to use with 5-accounts. Mozilla ignores the gazillion complaints of the issue. I'm going to look ...
I also have multiple email accounts to oversee, and the Unified Folders is not working, making it a nightmare keeping up with incoming messages. Please get a fix for this ASAP.
I just updated to 115.3.1 (64 bit). My setting is on "Unified Folders" and all folders are unified except the INBOX. No matter what I do it will not include the inbox. I tried numerous times and rebooted. Nothing. Don't you check out the changes ...