Ok if you want to remove the white skybox you can use this temp solution.

1. No clip out of the map behind the car dealership and you will find a white box outside of the map in the centre.

2. Fly inside of the white box, get your color tool out and set it to zero transparency (that's the vertical slider bar next to the color you choose.

3. Left click on skybox to remove the white and see the sun again :)

This will now allow you to use the Atmos or SimpleWeather addons if you have them to see night/day/weather (or just the sky if you don't have one)

This fix won't be permanent, sometimes if you clear all props it goes away and I don't yet know if this stays when you disconnect and others remain playing (as you have set the color)

I'm trying to get in touch with Sgt.Sgt. to fix this as well as the missing materials for a re-release.