eMail Import hangs up the database-inbox

I have imported a lot of emails via the apple-Mail-Plugin (around 30k).
After the iimport I can noht move 3k mails in the right database, is says
“the data has not arrived yet”
Actually I use a german version, it says:
“Datei noch nicht verfügbar”

Now I cant use the software anymore, as 3000 files in the inbox ar blocking me.

How can I proceed?
should I reimport all the emails?

Thanks for your help.

Welcome @ahenning
The message you’re reporting would be related to synced files, not email imports.
Is this on a second machine?