A Geogebra problem is showing blank coordinate system without the graph of the function that should be manipulated. This happened only for one student and only after he tried to reset it.
It is Contrib/CUNY/CityTech/Precalculus/setTrigonometry_-_Graphing_Comprehensive/per-phase-cosine.pg with random seed 997.
Even if I change his random seed and he gets a different question, the graph stays blank. Using the same random seed for myself I cannot recreate the problem.