Do the disabled wardrobe pieces have skeletons? I did some testing around and found out that “orphan” animation groups aren’t considered invalid GLTF, like this example file: AnimationGroup demo | Babylon.js Playground (babylonjs.com). If you drag it to the sandbox you’ll see that the validator returns that it is a valid file, despite having some warnings. I’ve tried in other viewers and they weren’t able to open the file, but that’s technically not following the spec since it’s a valid file 
However, trying to export the Alien test file, which has some skeletons Available Mesh BoomBox | Babylon.js Playground (babylonjs.com), and dragging it to the sandbox did generate an invalid file as per the validator, as “orphan” joints are indeed invalid per spec. So I’ll be pushing a PR that doesn’t export joints if they nodes they point to have not been exported, which fixes the invalid file issue.
EDIT: PR has been added Don’t export bones of nodes that are not exported. by carolhmj · Pull Request #13604 · BabylonJS/Babylon.js (github.com)