Also it seems that the "mute" button is somewhat broken or something - I have ~10 extensions and when I click "mute" on some extension, it will toggle mute on the second to the last.
Repeated clicking results in loop of 1) muting second to the last extension 2) muting the extension I'm actually clicking 3) unmuting second to the last and 4) unmuting the one I'm clicking :-D
It is quite hard to describe, I may create a video and upload it somewhere later.