Created attachment 105198 [details]
If you are deleting some recipients from the list, the recipient list changes unpredicatbly.
Difficult to explain, please take a look at the attached PDF
Ok I understand your bug.
But it will hard to fix it
We hide lineedit when we lost focus.
So when you try to click on "clean button" you change focus => lineedit is removed.
Really I don't have idea how to fix it.
Just noticed that this does not happen anymore (KMail 5.9.1, Apps 18.08.01), so closing the bug