Aquara/Xiamio Light Switch cannot be controlled from Phoscon when in group

I have a Group in Phoscon that contains one light (actually an Aquara/Xiaomi Light switch).
If I click on the light itself (marked 1 in the screenshot), the light changes in the GUI and the actual physical lamp also switches (as it should).
If I click the whole group (marked as 2), the change reflects in the GUI, but the actual lamp does not react. What’s worse, if I assign a zigbee switch to the Group, it also only changes the GUI, but doesn’t affect the actual lamp.