I normally play at 110% interface scaling and this issue still occurs for me at that scaling. Note that 110% is even more non-default that the normal non-defaults so if that's not supported, I can live with that :P

The workaround of using just the default 100% scaling works for me, so thanks ...

After starting a new game or loading a saved game (both in freeplay and sandbox mode), the actual world is not shown, and instead only a white screen (with a little bit of shadow at the bottom) is shown.

The main menu's background scenario's display fine. The introduction sequence for freeplay ...