Hi Regine,
it seems that the GeoGebra question type is only supported up to Moodle 3.3. and I have actually had problems with some versions of these questions running not stable.
The best would probably be if you integrate a geogebra applet via Java Script into a STACK question. You can have a look at this older discussion on this topic. Or you are using JSX Graph - but I myself are still at the very beginning with both solutions.
Stephan.