In the folder list on the left, next to the inbox folder, there is the number of unread messages, although all messages have been read. This mystery remains for many updates in a row. If you use a quick filter for unread messages, the list is empty. It can only be reset using the "mark all messages in this folder as read" command, but I'm not sure if I can't see some of the messages, maybe it's a synchronization bug?
