Black stage - neither shapes nor backgrounds are visible

After installing and starting Substance 3D Stager, my stage was just black. I can drag and drop shapes into my scene. I can also see a cyan square which indicates, where the shape will be dropped. But after droping I cannot see anything but that black stage. I can open scenes which I created earlier on another computer. But the stage stays also black. 

Maybe it is a graphic card problem? Is use the NVIDIA T600 Laptop GPU.

Thanks for your help!