Actuators are open but no flow

Hello everyone, in the DG in the heating circuit distributor, 3 out of 6 actuators are open but somehow there is no flow? The rpte float in the sight glass remains at 0 l/min. On the ground floor, 2 actuators are open and there you can also see flow.

Also, in the DG in the heating circuit distributor, you can feel no heat at either the supply or return. On the ground floor, you can feel heat at both the supply and return in the heating circuit distributor.

How do you know that the actuators have opened the valve? ERR active for all rooms/heating circuits? Please show the heating circuit distributors EG / DG. Addition: I just read that you have already been tinkering around. Then write exactly "What happened so far". HKV in the DG is "clogged"? How old is the system?

On the ground floor, 2 actuators are open and you can also see flow there

Why only 2 and not all 5, 6, 7...?

Why only 2 and not all 5, 6, 7….?

Currently, only the bathroom, guest toilet, and the children's rooms are heated

How do you know that the actuators have opened the valve? ERR active for all rooms/heating circuits?
Please show the heating circuit distributors EG / DG.

Addition: I just read that you have already been tinkering.

Then write exactly "What has happened so far".

HKV in the attic is "clogged"?
How old is the system?

The system is 4 years old. I simply suspect that the actuator has opened the valve, can I do this manually?
I had cleaned the Strawa Regolux sight glasses, after I screwed them back in nothing happens anymore.

Attached are pictures of the HKV in the attic. Actuators for the bathroom and child rooms 1 and 2 are open, I hope the valve is then open as well. ERR are set to 6, the highest level.

Really stupid question: Have you ever turned this black knob on the sight glasses all the way open? You can easily open the control valve manually by turning the top part (blue) to "manual".