Put the summary of the bug you're having here

What I expected to happen was...:
I put /gamerule doDaylightCycle off to fight mobs and expected the moon to freeze in it's position.

What actually happened was...:
The time was frozen but the moon was slightly twiching up and down.

Steps to Reproduce:
1. go into creative mode and do /time set 14000 or /time set night.
2. Once the sun is completly down, do /gamerule doDaylightCycle off.
3. Look and the moon and notice that the moon is slightly twiching up and down, I'm inferring that the moon is trying to do it's cycle.
*It might do it with the sun as well, I'm not sure.