Missing Mail in custom folders

Missing Mail in custom folders

It seems that in some of my custom subfolders the emails stored are missing but the counter on top right shows the email count right and i can navigate it.
No sign of the emails although they were stored there and not archived.
Also when i toggle the layout the emails are accounted for but do not show up in the list view.
Even searching for the user's email affected the search results show the right number but no emails.
Please help, would be much appreciated!