Features from add-ons dont generate in realms

I tried to add an addon on my realm wich adds more structures but when I try to generate new terrain in the realm (not generated in world creation that is) the structures don't generate!

Steps to Reproduce:
1. Download an add-on that adds structures or new ores in minecraft (I tried https://mcpedl.com/rocks-plus-addon/)
2. Create a world with the add-on (activate experimental) and add the world to the realm
3. Make sure the realm has the add-on (behavior and resorces) as well
Observed Results:
The structures appear only in the terrain generated in the world creation and they dont generate on new terrain!
Expected Results:
The structures should generate in newly loaded terrain since the add-on is added to the realm