anonymous user - Sharing this with broader community.
Issue: Error message experienced while creating a Resource Group from within a Management Group, and the Resource Group not being listing under the Management Group itself after it is created.
We collaborated with our internal team to fix the error message.
We mentioned that by design, a Resource Group is listed under a Subscription, which is further contained by a Management Group (i.e., a Subscription is required to be in the Management Group of interest).
You confirmed the error message fix.