Fog Tickbox is suddenly always disabled on startup?

Hey guys,

Randomly, my ‘Fog’ setting has suddenly started defaulting to OFF on Startup.
Has anyone else had this issue?

I have to keep going to the menu to turn it back on everytime I load the level?
Its a small issue, but its one of those things where I have to keep doing it and now its really starting to annoy me.
It doesn’t happen on any other computers with the same project on the same engine version.

To clarify, I have never opened or tampered with any of the project/unreal start up code.

If someone can help solve this, I would be greatly appreciative!