Until last night.
Because the current weather is typical lowland weather in the boggy old sea marsh surroundings where I live: without much wind and continuous light rain, fog or wet snow. So to my surprise this morning (see screenshot) the wind had it totally wrong. Windspeed meters have the bad habit of being mounted in most awkward places but this one is not too bad: just at the other side of a totally muddy horse pasture, 50 m from my house so dismounting was not to big an effort.
When lowering it and holding it horizontally, I saw the water gushing out: apparently, there is a reservoir where the transmitters and the microphones are absorbing the ultrasound.
After it had been emptied and remounted it was working again (see screenshot).
So if you have an awkward place to mount the windspeed meter, take this into consideration.
I will notify Ecowitt as well, a minor redesign with a water drain may be useful!
[EDIT: forgot the screenshot]