When using an empty bucket on a water source, the bucket becomes a water bucket visually. Despite this, the water source doesn't dissipate, and the bucket does not place a water source when used. This "phantom water bucket" then returns to being an empty bucket. Disconnecting and reconnecting fixes the issue.

This most commonly happens on servers but has happened several times in singleplayer as well. This behavior is not consistent and may be hard to replicate.

To replicate:

1. Have a water bucket
2. Empty the water (into an air block)
3. Very quickly take back the water