[2018.3.14f1] Script Association Errors
The referenced script on this Behaviour (Game Object 'UiManager') is missing! The referenced script on this Behaviour (Game Object 'MapView') is missing! The referenced script on this Behaviour (Game Object 'MouseCursor') is missing! The referenced script on this Behaviour (Game Object 'GameManager') is missing! The referenced script on this Behaviour (Game Object 'Main Camera') is missing! The referenced script on this Behaviour (Game Object 'NetworkManager') is missing! The referenced script on this Behaviour (Game Object 'SceneRoot') is missing!

I'm honestly not sure why this happens. Had someone else report it too... However, for me, even if cloning a fresh version, it doesn't break for some reason.
Are the scripts visible in the menu/selector if you try to assign it manually? (behaviors are named the same as their GameObject)
Yes, scripts are visible. I can add Game Manager manually and it will display correctly.