Good morning, I has been using Thunderbird for my email account for several years. For the first time I encountered a problem that Thunderbird seems not to see sub folders I have created on the IMAP server. They suddenly disappeared and when I go to synchronization, the program does not open the list to select folders to download. I tried to restart computer, close and open thunderbird, but nothing seems to help. I will appreciate advice or assistance. Kind regards, anna.