Problems with underfloor heating in a room

Hello,

a room on the ground floor of our house is obviously not being heated by our underfloor heating.
The thermostat and the actuator on the distribution box show activity.
Before I commission a heating company, I wanted to ask for your advice first, whether one might still be able to do something oneself?

Best regards
Free

Which room is it?

How was it determined that nothing is heating there, and what do the thermostat and the actuator indicate?

And what does the heating circuit distributor indicate? Is there any flow at all? Please show some pictures. ERR active?

Which room is it? How was it determined that nothing is heating there and what do the thermostat and the actuator show?

The study. Well, you can notice it compared to the other rooms. We also have a thermometer (19 degrees). The thermostat is analog for us, adjustable in 6 levels. There is a red ring (active) visible on the actuator.

And what does the heating circuit distributor indicate? Is there any flow at all? Please show some pictures. ERR active?

How do I determine the flow? Attached is a picture of the HCD.

If the pipe is warm, you have flow. Are you sure that all rooms and thermostats are correctly annotated? Quite a lot was messed up in our office. One problem was that the thermostats controlled the regulator for the neighboring room...