The ender dragon dazed out after a few rounds. This occurred on a Realm.

Steps to reproduce

1. Fight the ender dragon a few times in a row.
2. When it comes down to perch, circle around one of the obsidian pillars and then head back toward the dragon on the fountain.
3. Bump the dragon.

Expected result

The dragon does not change position while perched.

Observed result

The dragon while perched started to sink downward through the fountain pillar and then drifted toward the side and into the ground when bumped.