What the title says. RoC upgrades show up without issue, and all upgrades appear in a map’s Object Editor. They can be selected in the Object Browser, but new upgrades referencing an old one as a base disappear once created. This does not happen with the units missing from the Campaign Editor tree. It does, however, happen with abilities as well.
EDIT2: Okay, the cause seems to be having the Campaign Editor open when loading the Editor.