Citing @macmarrum
Filter Composer is misleading the User, claiming that the condition is true (it shows a magenta bubble around "Werbemaßnahmen terminieren"), whereas the Map Conditional Style Engine is refusing to apply the style, because the condition relies on another condition
See video
And here the map
preview 1.9.11_02
Preview 1.9.11_05
I reverted the last change because it made some maps non responsive,
but now the filter composer should behave correctly