End Stone around the Obsidian Platform Drops when entering the End for the First time

Put the summary of the bug you're having here

What I expected to happen was...:
The Obsidian Platform Spawns in the End, if surounded by End Stone the Blocks get replaced

What actually happened was...:
The Obsidian Platform Spawned in the end and the Endstone Blocks Dropped upon entering the End, beeing able to be picket up.

Steps to Reproduce:
1. Find or build an End Portal
2. Enter it and hope for the Obsidian Island to spawn inside the End island
3. Blocks Should Drop

Seed i used for the World:
-4811746627093218166