In Minecraft Bedrock Addons, world generation features such as features, biomes and feature rules don't seem to work after exiting the world for the first time. 

Steps to Reproduce:

1. Create a addon with a feature and feature rule/biome

2. Go into the world and look at the feature generate

3. Exit the world

4. Go back in and go to unloaded chunks and search for the feature

5. Notice it not spawning anymore

Expected Behavior:

After exiting and rejoining, it should still be generating.

Actual Behavior:

It doesn't spawn.