Gamerule Problems

When creating a new world I often use the new game rule feature in the create world menu. Recently I have been noticing when I set up the game rules I want and then create the world, the game rules don't save. For example, if I turned off mob spawning in the game rule section of the create world menu, when I enter the world mobs will still spawn. This is also the case with mob loot, if I turn this off mobs will still drop mob loot.

Please fix this bug!
Thanks Mojang, the game is amazing anyway.