I can't reproduce this bug for some time now. Several months ago I wanted to see if I can still reproduce it, so I commented out 'load-module module-switch-on-connect' in /etc/pulse/default.pa
I wanted to test it for some days but then I forgot about it – it just worked (for several months now). I use Debian Testing, so that's gnome- control-center 3.30.3 now.
