Closing & reopening Thunderbird makes O365 mailbox disappear

I am using Thunderbird with Office 365 to make use of the message filters capability in Thunderbird (It works better than Outlook). However, when I close Thunderbird and re-open it, my inbox is missing and it only shows the "local folders". I do notice however, that a 2nd tab in Thunderbird briefly opens and then closes quickly. I recorded the screen and was able to pause the video to see that the brief window opening is actually the Microsoft login screen for OWA. The only way I've been able to fix it is to recreate the profile in Thunderbird and copy over all my message filters by moving the dat file and replacing the default. I've done this about eight times now and am getting frustrated. Is there a fix so that Thunderbird retains my 365 mailbox?