Light awake detection doesn't work

So I activated the light awake detection on my Huawei P30, mainly to measure the change of light in my bedroom in the morning.
But in the Graphs there is no orange (yellow?) Line that shows me the light changes.

Any idea what could cause/fix that?

How bright lights do you have? The graph is only shown if there is consistent 30+ lux light.
See this topic: Light level not always recorded

I don’t know the lux level exactly but your explanation sounds plausible. I think that’s the problem in my room.