Structure not Spawning in Test world

I am making a custom dimension with a custom structure. When i clicked on "Create new test world" and created the test world, went to my custom dimension, my structure didnt spawn. But when i did the same thing with a normal world, the structure was there and there were no issues. I dont know if this is intentional, something that happens with everyone or just something that happens to me. If someone could explain this, it would be great.