I had no problem in 20 with your original mask of 7.
But I see from your image you are still in the GDL editor 3D preview.
I was looking at the actual Archicad 3D window.
Maybe the shadows just don’t work in the GDL 3D window?
Versions 6.5 to 22
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision M6800 - i7 4700MQ @ 2.40GHz, 16GB RAM, AMD FirePro M6100 (2GB), Windows 7 64bit