Hello Lee,
So there are a couple of troubleshooting steps that you can take.
It does appear to be a culling issue. Where an object is being rendered really quickly on screen and is returning a white value.
1.) Enter this command and build lights, then play. r.hzbzocclusion 0
2.) Try to isolate in your project which asset is causing this issue specifically. For instance if the wall is modular and it’s the wall causing the glitch then dig through the material properties to see what could cause it.
a.) If you have emissive turned on then try turning it off, once you have found the problem asset.
Let me know if this helped or if you are still experiencing this problem.
Thanks,