[4.12] Strange artefacts coming out of 0,0,0 only when I launch the program and not in play mode

This seems to work totally fine when I press play, but if I launch and it cooks the program then I am getting some weird artefacts coming out what appears to be the 0,0,0 position.

This project is set up on 6 separate maps, 4 houses, a courtyard and the surrounding area. I am using the landscaping tool on most of the landscaped areas, it looks like a bush. This only seemed to happen on 4.12?

Can someone please give me some assistance on this. I have been trying to fix it for days

Please help somebody :frowning:

This is driving me absolutely crazy