Empty chests after optimizing

After optimizing a world from the 1.15.2 to the lastest snapshot. Most of the loot chest from the Bastion are completly empty. 

What I expected to happen was...:
A normal world generation

What actually happened was...:
Errors while optimizing

Steps to Reproduce:
1. Create a world from 1.15.2 (doesn't matter if you're in survival or creative)
2. Load the world and go to the nether once
3. Load the 20w22a snapshot and optimize the world

4. Look for a bastion and the chest will be empty