We successfully resolved error code 29 for one of our customers! We don’t know the exact details, but it had something to do with the Room needing to be upgraded (either the version, or the license/subscription).
It was not an error in our code or our usage of the Zoom API. The only changes made were within the user’s Zoom account, not our code. To be crystal clear, we are using the standard Zoom OAuth API create meeting endpoint with the room set as the host.