I have exactly the same problem.
About Configuration Service I am testing with exactly the same coding as the submitter.
Submitter says that the contributor solved by updating Developer Rig,
but I am Undefined even if I make Rig the latest one as of November 15th.
My Extension is running Rig and Host test, but Configuration Service only does not work well.
My Developer dashboard [Extension Capabilities]
[Select how you will configure your extension] is checking [Extensions Configuration Service].
I would like you to tell me if there is anything else I have missed.