Thunderbird is downloaded new messages, but I can only see the Welcome to Freedom screen and cannot click into and see any emails in any folder

Thunderbird is downloaded new messages, but I can only see the Welcome to Freedom screen and cannot click into and see any emails in any folder. I see that numerous emails were downloaded, some going to the inbox, other into the spam folder. However, when I try to view them, all I see is the Thunderbird "Welcome to Freedom" main screen and cannot view any emails in any folders. Clicking onto different emails and their folders all show that same main screen.