Is this an IMAP account? If it is, right-click the account in the Folder Pane, Subscribe..., Refresh. Do the folders appear in the list but not checked, i.e. not subscribed?

No, I have 2 pop accounts. Also, I had a bunch of archive local folders that are not showing up in the folder pane

Help/Troubleshooting, Profile Folder, Open Folder, close TB. Open Mail/Local Folders and look for mbox files - large files with no extension, named after folders e.g. Archive - and delete the .msf files with the same names as the mbox files e.g. Archive.msf. Restart TB and see if the folders appear under Local Folders in the Folder Pane.

Thanks for the reply, there is a little progress, I recovered one sent folder for one of the 2 accounts. Foe the archived folders, no progress. In the "Mail/local folders" folder, I have an "Archives.sbd" folder that contains all my archived folders. In each folder, there are .msf files

Should I delete all the msf files everywhere?

Yes, delete the msf files in the sbd (subdirectory) folders. They are automatically rebuilt when TB restarts.

OK, I did it but no change: still no archived folder listed

I will have to revert to version 68 and block any update ... too bad I'll lose all saved messages since my last backup.

Check the account subfolder, e.g. Mail/pop.gmail.com, for any archive mbox files and copy them into Mail/Local Folders. Otherwise, mbox files from your last profile backup can be copied in the same way.

I have no pop.gmail.com subfolder, I have mail.messagingengine.com, mail.messagingengine-1.com, pop.mail.yahoo.com, pop.mail.yahoo-1.com, plus.pop.mail.yahoo.com, plus.pop.mail.yahoo-1.com and smart mailboxes and none of these folders contains any mbox file

I have found no mbox files

I have no gmail folder, my mail subfolders are listed on the attached pic

Mail/pop.gmail.com is just an example. The folder name corresponds to the POP server name, of which there are 9 in your profile. There may be folders with -1 in the name if the account has been removed then re-added.

I doubt that the update deleted any folders, but they may have been hidden if the containing folder is no longer read by the current account setup. Look through all the subfolders of Mail and compare the dates of mbox files with the same name.

I found no mbox file anywhere I can see my archived folders and files in the mail/local folder, but they do not show on the folder pane