I changed the spawn chest to not be initial chunk only and changed the chest contents to world core, and there is no chest in my initial chunk so I'm stuck. What I wanted to happen and expected to happen, is every chunk would have a chest at y-60 (as the config says and is the default setting), with a world core in it. Did I do something wrong?

That is how it should work, yes.

Edit: Saw you have the minecraft version in the title and tried with Forge 1.20.1. Was able to reproduce the issue.

So that confirms it as a 1.20.1 issue? Good to know.

Addressed in 2.1.0