Hue sensor not reachable, while it is reachable

Hi guys,
I’m using a Conbee 2 stick with Deconz in my Home Assistant. I have some Hue sensors around the house that sometimes report to be unreachable. The strange thing is that the sensor reports “Not reachable”, but in the topology view (or whatever it is called) of Deconz, I can see that the connection is pretty much perfect. The sensor is close close to the conbee itself and is also close to a Tradfri plug. I have seen this behaviour on multiple sensors, but not on all of them.
Anybody know what can be the cause of this issue?