Folders disappear or migrate to 'More' or 'Archive'

I have 13 email accounts within eMClient (one gmail account as ‘SMTP’ and 12 others as ‘General’), and 29 folders at the ‘top’ level, many of which are divided into sub- and sub-sub- folders. Probably about 100 in total.
After 2 or 3 years, I am finding that folders disappear, sometimes migrating to ‘More’ or ‘Archive’. I have not invoked any such migration.
When I cannot see a folder anywhere, I can sometimes see it in the list that comes when you ask to ‘Move to folder …’ a message to a different folder, but it appears nowhere else.
What is needed (IMHO) is a ‘Find folder’ facility using the same code that the ‘Move to folder …’ but immediately available from the main menu.
If the folders that disappear are still extant, then there needs to be a review of the code to find out why the folder structure is (or appears to be) unstable; if the folders are disappearing, then on my side I am headed for a serious rail-smash.
I hope that there is a simple answer …

If the folders appear in Move to Folder, then they have to be there somewhere within or under the account folder structure. They may have also been eg: accidently moved to (another account folder) as ive personally done sometimes with multiple accounts when i was eg: a bit sleepy.

If they are not visable anywhere under your account folders or any other acct folders as normal, or at the bottom of the specific account under (+more), then could be the specific acct missing folders are (out of sync) with the mail server & may have some sort of corruption within your specific acct database locally.

So apart from Restoring an eM Client backup prior to the problem, via “Menu / File / Restore” if they are all IMAP accounts, do all the missing folders / sub foldes appear in your accounts online in webmail ?

If all the missing folders / sub folders (do appear ok online in webmail), then suggest to remove the problem IMAP accounts and re-add them which normally fixes that type of thing.

Gmail also has the option (as you have that) to repair it in eM Client which can re-sync all your mail and folders from the mail server, which can then sometimes avoid having to remove and readd your acct. To repair Gmail, right click “All Mail” and click “Properties” at the bottom. Then click the “Repair Tab” at the top and run the repair.

Obviously before removing any accounts, backup eM Client first via “Menu / Backup”. You can also setup automatic backups, via “Menu / Settings / General / Backup” if you don’t do that already.

Thanks CZ - they are all POP accounts so no question of syncing.
I am shifting to another email client - sorry!