After a fresh install of macOS Big Sur (11), I tried to migrate my Apple Mail configuration and the mail messages stored locally.
First attempt was to copy the ~/Library/Mail/V5
content to the new ~/Library/Mail/V8
folder.
But the local mail folders didn't appear. Even no section for the local folders in the left side bar. Nevertheless, Mail showed up the converting message at the first start.
Second, I tried to copy the whole ~/Library/Mail/
folder and the ~/Library/Containers/com.apple.mail
folder.
Again, at the first start afterwards, the converting message showed up (this time a little longer). But the result is still the same, I can't find any of the local stored mails and the folders.
Am I missing something?