This is an EA ‘feature’. For elements which are just created in a package, EA doesn’t save their order: they seem to be able somehow get them in the right order in their UI, but at the API which we have to use, the order isn’t fixed.
BUT, all you have to do is select one item in the package, move it up or down one, then move it back to wehere it was, and EA suddely remembers the order of ALL the elements in the package.