Liquids not flowing/not always flowing

Liquids do not always flow correctly

What I expected to happen was...:
I hit a block and expected the water/lava to flow into the empty space.

What actually happened was...:
The water/lava did not flow into the empty space

Steps to Reproduce:
1. Create a new world (must be a new world)
2. Find a pool of water or lava
3. Destroy a block to allow flow

May only occur on Large Biomes worlds.
May be fixed with some persistence on the player's part, but no guarantee.