No sound on Group after editing automat.

I was playing around with the filter automation in the GroupChannel Bassline, when suddenly sound output stopped.

Doubting that it was something I wrote into the automat by mistake I deactivated the Filterplugin.
Still no sound.
I rechecked the routing: nothing…
Please see the attached screenshot for the phenomenon…
I later realized that some output is produced, but for a reason unknown to me, the audio output is lowered by 50 dB… for apparently no reason…

I had this issue pretty often during the last days (audio on certain (not all) channels suddenly stopped), and i don’t know why.
For me it looks as a bug, but it’s not reliably reproducible…
e.g. if I reroute the single channels to another group channel they sound…
if I reroute them back to bassline group, sound is lowered to -50dB
simply makes no sense to me… I am not aware of something I could have pressed which could produce that result.
RoutingProblem_NoAudio.gif

hmmm… just a single system glitch that noone answers?