Aqara Water Leak Sensor - Unknown Status for moisture sensor

Hi all,

I just added one of the Aqara waterleak sensors via Z2M and that went fine in general. Device is present, I can also see most of the exposed sesors or values

But unfortunanetly the important one (waterleak/moisture) always stays in state “unknown”.

I have removed the device from Z2M and re-added it several times. Removed the battery, etc.
Still, only the moisture sensor never has a state available.
Interestingly, when I check the “state” tab for the device in Z2M I see:

{
    "battery": 100,
    "device_temperature": 26,
    "linkquality": 144,
    "power_outage_count": 12,
    "trigger_count": -1,
    "voltage": 3035
}

which is also missing the moisture sensor/value.

Anyone got an idea what the problem might be?
Is there a way to debug the MQTT messages the device sends?

BTW: I have several Aqara Zigbee temp/humidity devices running without problem…
Zigbee Stick is a SONOFF Zigbee 3.0 USB Dongle Plus