kde neon user systems with kmail 5.5.*:  (bug is on my laptop and desktop)

* select *several* messages in the message list of folder A (I used shift-click)
* move them to folder B (or delete them)
=> Messages are still shown in msg list of A

Expected result:  Msgs are not shown anymore in msg list of A

Additional Info: 

* When I goto folder B the moved Msgs are listed there. (Good)
* When I now go back to folder A to Msg are still listed there. (Bad)
* I can try to select and move/delete them again:  List listed in A (Bad)
* When I exit & start kmail again, the Msg are no longer listed in A.  (Good)

So it looks like everything works fine, except that the Msg list entries are not remove from the listing of folder A.

Note: with single msg.  Delete and move works as expected, bug is only with several msg at once.