Since the update to OpenHAB 4.0.1, items that are defined as a group in the sitemap are no longer displayed correctly, the control elements are missing for all items except one and that is always a different one.
Group:Number:Temperature:AVG gTemperatur_soll "Wohnung Temperatur soll [%.1f °C]" <temperature> (gWohnung)
Frame label="Heizung"
{
Group item=gTemperatur_ist
Switch item=gTemperatur_soll mappings=[16="OFF"]
Group item=gTemperatur_soll
}