Junk Mail (marked as deleted) are unread in eM Inbox and not possible to delete.

Title says everything.
I know there are some similar issues in the forum, but in my case it’s my private server and the spam handling is no problem with all other clients. 
When I look in my inbox via webmail the regarding mails are marked as deleted. In eM Client they are unread and I’m not able to open/move/delete them.
Only way to get rid of them is deleting it with webmail.
That’s the only issue so far - except of this (for me a huge issue!), I would like to buy eM Client. 
Pls help!

I found out, that deactivating the “threaded view” (I have the german client; it’s called “Unterhaltungsansicht” there) will let disappear those “unread but deleted” mails.
But that should not the solution for it!