realm doesn't exist on the current cluster" B2C Commerce Developer Sandbox

Question

I am getting below error when creating a sandbox on B2C Commerce Developer Sandbox (demandware)

{ "kind": "Status", "code": 404, "status": "Failure", "error": { "status": "Failure", "message": "zzxp: realm doesn't exist on the current cluster", "reason": "RealmNotFound" } }

realm zzxp is active. I am not sure what is the cluster and how to find it.