Hello TomHat, all,
thx for the offer to replace the daslight. We went to out local shop with this discussion and got a new daslight from them.
The bad news is that the blackout issue also occurs with the new daslight.
It seems to be very bad luck, very unlikely, that both daslights have the same problem .
As workaround I will place now a scene into standalone mode.
Most likely I will rebuild the full dvc and era configuration from scratch now. Unless someone else has another idea / hint.
It's kind of frustrating.