As I ran into the same issue this morning, I uploaded my files to twitch and in “hosted test” mode, the same commands are setting the new config properly.
So test your config handler once in hosted test and then use the dev rig config service for local development.
Afaik there are several things not implemented (yet?) into the dev rig, so for example the pubsub whispering will not work in the rig too, meanwhile pubsub broadcasts are received…