Coupling of features, which is that when you fill it, you can click on other bodies to copy the fill it value, you can copy a, fill it from the same body. Sometimes it works, it won't highlight, and there are edge cases where it won't work, like if you copy. So at this point, I think, yeah, it won't work there.

You can copy in some from the same body in some cases, but normally it's easy to copy from other bodies.