It's incredibly irritating and certainly a bug, when you've disabled the multiplayer element but you're still unable to change the time through the quick access bar at the top of the screen. Especially if you're trying to enjoy the scenery.

The trick is to enable Developer Settings in 'General Settings' (it's down the left hand side). This brings up a persistent menu at the top of the screen. Within there, there is an option to force-change the time of day.