The Bug:

You cannot fly and sprint simultaneously in creative mode when only the lower half of your body is submerged in water.

Steps to Reproduce:

• Switch into creative mode if not already.
• Summon a large body of water below you that is only a singular block deep.

• /fill ~-10 ~-1 ~-10 ~10 ~-1 ~10 minecraft:water

• Submerge the lower half of your body in the water and begin flying.
• Without changing your y level, attempt to fly and sprint simultaneously.
• Take note as to whether or not you can fly and sprint simultaneously in creative mode when only the lower half of your body is submerged in water.

Observed Behavior:

You cannot fly and sprint simultaneously.

Expected Behavior:

You would be able to fly and sprint simultaneously.