I had this issue before with earlier versions of Thunderbird and I can't remember how to or if there is a solution. I have the latest Thunderbird 78.3x or something (just upgraded today.) The quick key folder navigation works but when you close and then reopen the program it doesn't work again. You have to go back into the add on manager and enable it again. I uninstalled and reinstalled the add on, but still no solution.
What is the solution if any? Thanks for any help.
They Ask Me If I'm Happy; I say Yes.
They ask: "How Happy are You?"
I Say: "I'm as happy as a stow away chimpanzee on a banana boat!"