Notification popups for already read and deleted mails

I have this recurring issue where email notification popups show up for mails that I have already read and deleted.

Steps:

  1. Open the application
  2. New mails are being downloaded and show up in the inbox
  3. Delete those mails fast (Shift+Delete in my case)
  4. Minimize the application

=> After a few seconds Windows system notification popups show up, exactly about those mails that have just been marked as read and/or deleted.

It seems like mails are not taken fast enough out of the notification queue.

Setting are like this:
image

Version: 9.2.1222 (ca10485)

Anyone else with this problem?