I'm running Thunderbird 115.8.1 (64-bit). On Jan. 29 I left the beta program after several years to return to the release version because of problems with the beta at that time. Last year, still in TB Beta, I had switched my two email accounts from POP to IMAP. At that time I moved all my mail folders (except inbox, trash, and other system folders), and about 14 years of archives, to the Local Folders account to avoid the cost of storing them on a mail server. There were no problems. At year end I archived my 2023 emails from my folders in Local Folders to my archive in Local Folders, preserving the folder structure, and everything worked normally. When I left TB Beta a month later I tried to replicate my folders, including the archive folder, in the new profile for TB 115. Then I manually moved folders from my TB beta profile to my new profile folder (C:/Users/billf/AppData/Roaming/Thunderbird/Profiles/84xm6dz9.default-release/Mail/Local Folders/). The folders showed up within Thunderbird, then some of them disappeared briefly but then reappeared. A few days later about 80% of my folders, including the archive folder, vanished completely and haven't returned. I checked the file system and they were gone. Today I tried again, restoring several .sbd folders and .msf files - most importantly the archive - from my HD backup from mid-February when everything had seemed to be working. They're still in the file system - so far - but none of these folders are now visible in TB. The account settings for Local Folders don't mention archiving at all. I hope someone can tell me how to get my old folders and especially the archive back, and stable. (As I rebuild my folder structure in TB I'm giving the folders new names so they won't be overwritten if my folders from January come back.)