Problem when using 1-wire AAG hum/temp sensor as main humidity

I’m using an ULTIMETER II weather station and have connected one AAG baro/temp as well as one AAG hum/temp sensor. Sensors work fine via the AAG USB link.
Both, the humidity and temp values are correctly shown on the WD page as “Indoor temp.” and “Indoor hum.”

When I try to use the AAG hum/temp sensor as my main humidity sensor the humiditiy value indicated on the WD page shows 50 % instead of the currently 91 %.

Any hints?

Thanks a lot!