New Folder FAIL--Deletes itself after five minutes

I’ve tried creating new subfolders every way I know of and every time the new folder disappears after five minutes. AND all the messages I’d put in there is also gone!

What version of eM Client are you using? (Menu > Help > About)

What errors are you getting? (Menu > Tools > Operations > Log tab)

How is your account setup? IMAP, POP3, Exchange?

Who is your email provider? Some providers do not permit sub-folders, or have a limit on the depth of folders.

Version 7.2.36908.0
I’m not getting Any error messages. The folders simply disappear.
I don’t know how it’s set up. It self-installed with few questions to me. It used my previous mail handler as a guide.
My provider is Yahoo. It had let me have subfolders with my previous Outlook and Mozilla Thunderbird.