start plasma session, open dolphin, select some file/folder, press shift+del, cancel file/folder deletion, right click sound icon in the system tray, select "Configure audio volume...", click "Audio volume" section, click "applications" tab, click the button to mute/unmute the notification sounds (above percentage). Result: mute/unmute button changes visually but the state of the "Notification sounds" feature remains the same. Click "Notification sounds" slider, click mute-unmute button again: now the button works as expected.
*** Bug 395293 has been marked as a duplicate of this bug. ***
Git commit fbdef07f554bbec59d6142837fdf44afd103f6dc by Kai Uwe Broulik. Committed on 11/04/2019 at 07:27. Pushed by broulik into branch 'Plasma/5.15'. [StreamRestore] Don't mess with channels Just set volume for all of them. Otherwise when just calling setMuted, we will send the original volume struct, which might have multiple channels, with a hardcoded channel map that only has one channel. PulseAudio then refuses to write the settings. Patch ported from pulseaudio-qt FIXED-IN: 5.15.5 Differential Revision: https://phabricator.kde.org/D20450 M +4 -4 src/streamrestore.cpp https://commits.kde.org/plasma-pa/fbdef07f554bbec59d6142837fdf44afd103f6dc