KevinTheJedi
I've done another reinstall, now the records are there. Idk what it was, maybe I missed them, maybe they weren't there, anyways, sorry for that.
I've now been able to fix the issue thanks to this where you suggested to delete any records from the email_account table, that don't have a matching record in the email table. After that, fetching worked again.
Thank you for your time and help in this case.