Error while toggling "Make Public" service setting

#Trailhead Challenges

I got the following error while trying to enable make public configuration to do the mock api testing in anypoint design center as per the trailhead "Test the API Specification". Please advise 

{ 

  "info": { 

    "platform": "Chrome 156.0.0.0 on Windows 10 64-bit" 

  }, 

  "error": { 

    "type": "BadRequestError", 

    "message": "Bad request", 

    "errorCode": 400, 

    "errorBody": "The request content was malforme

d:\nSubstream

 Source(EntitySource) cannot be materialized more than once", 

    "response": {}, 

    "options": { 

      "headers": { 

        "Cache-control": "no-cache", 

        "MS2-Origin": "API Designer", 

        "MS2-Project-Owner-Id": "813f643d-804e-4122-926f-e1d86878c0d6", 

        "MS2-Project-Organization-Id": "0c121e78-30f4-4453-bdf3-a0ce90c076e0", 

        "MS2-Authorization": "Bearer xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 

        "Pragma": "no-cache", 

        "Expires": "0", 

        "Content-Type": "application/json", 

        "MS2-Main-File": "quickstart-store.raml" 

      }, 

      "body": "{\"expirationDate\":null}", 

      "method": "POST", 

      "credentials": "same-origin" 

    }, 

    "name": "BadRequestError" 

  } 

}