Created attachment 105198 [details] Error description 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