setShadowDistance scripting command changes user set value in CONFIGURE->VIDEO->SHADOW and saves into user profile. Restarting the game does not set shadow distance to user set value.

Shadow distance set with script either in editor or MP stays persistent even after whole system restart.

What this means if if you joined a server where custom shadow distance is applied by mission maker, when you leave you have to manually reset shadow distance in your config menu or any other server you join or when you open editor, the shadow distance will be that of what it was set with last setShadowDistance command.