Hello,
I am encountering some issues to delete folders in kmail 5.2.3

OBSERVED RESULT
When I try to delete local folders oftenly they are not really deleted.

EXPECTED RESULT
They reappear after I reopen the program.
Or sometimes when I go to an other folder

I found a kind of workaround by manually deleteting the emails in the folder then I delete the folder itself.
Before leaving the program, I update the parent folder (F5) and the parent folder and its subfolders (Ctrl+F5).
But it is painful when there is many folders to remove.

Does anyone else had this issue?
I would also volunteer to investigate the code and to provide a correction

SOFTWARE/OS VERSIONS Debian 9
Linux/KDE Plasma: 5.8.4
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 5.28.0
Qt Version: 5.7.1

ADDITIONAL INFORMATION