Follow-on mutable functions don't seem to work

Summary: Not sure of the details here, but noting it for investigation.

For the Arisia Space, I tried to build some QLButtons on a "parent" that would, when clicked, create a "child" using _createThing, and then modify a list on the parent to point to that child using _changeProperties. This consistently didn't seem to work, so I worked around it, but it's worth making this function as expected.

These knock-on effects should follow the QL maximum depth, but it should work.