welcome to the 
forum, @ludwigsiebzehnruebl
I’m still very new to Geomap myself, but I would check out this example on play:
https://play.grafana.org/d/o8jKigonk/0-new-features-in-v8-3?orgId=1&editPanel=95
the one thing that I notice: that example is visualizing a single table. But your flux query is returning multiple tables: I can see the select box at the bottom of the table:
Have you tried experimenting with some of the built-in transformations like merge?
maybe getting all your data into one table is important to the Geomap’s data model? Just a thought…