When I loaded a world that I use for all the snapshots I do, time was frozen even though doDaylightCycle was set to "on" at the beginning of the game. I tried doing /time set day but it didn't unfreeze and when I did /gamerule doDaylightCycle off and then I did /gamerule doDaylightCycle on but time was still frozen. I froze time in this map before but if I remember right, I did unfreeze time before the end of the game.

I created another world to see if it froze time there but it didn't. It was just a normal minecraft world.

I say worlds that were created before the new snapshot are effected I think.