The loudspeaker-icon in the systemtray is not rendered and the 'placeholder' (empty) space does not have any functionality/click behaviour. Next step: right-click tray-options, select visible systray-items, deselect audio/loudspeaker, klick apply, reselect audio and click OK. Then, the placeholder space in the systray is filled again with the loudspeaker-icon and with full functionality. Reproducible: Always
*** This bug has been marked as a duplicate of bug 352055 ***