GMAIL all folders empty

I set up an GMAIL account. All folders are there, but no mails. So, all folders are empty. IMAP is activated.
Any suggestions?

Thanks!

I was having this issue too, and was just able to solve it for my account. I went into my Gmail settings, and turned off all my custom labels. In particular, I had some named like [Gmail]/Label, and I suspect those might have been the issue. To turn them off, I just unchecked “Show in IMAP”.