This has been happening for [strike]a while[/strike] months now for me; I’ve posted about this on the main site’s ROBLOX Studio forum but got no response and the thread died.
Big Part objects cast shadows on the 3D-rendered skybox, as shown in the above screenshot. The baseplate’s shadow is being cast on the skybox and rendered right through the 3D primitive itself.
I’m not sure if it is hardware specific or just drivers, but the only way to fix it is just disabling shadows altogether. As for settings to reproduce, I’m at a loss. Here is the “profile” heading in Setting’s Diagnostics:
Perhaps those shadows should just be merged with dynamic lighting in some way? Dynamic lighting is the same thing as shadows, but with another approach and much more elaborate.