REST Issue with GetOprOpCodeInfo

I have a case open with support and they are being incredibly un-helpful.

I can create a quote through REST no issue on my account. We have an account for an external application that can create a quote in Epicor when signed in no issues. When the same account tries to create a quote through REST it always fails out at GetOprOpCodeInfo.

Does anyone have any ideas as to what could be going on? Like I said, the account can create a quote in the client, just not in REST.

Sorry, forgot the error.

{
  "HttpStatus": 400,
  "ReasonPhrase": "REST API Exception",
  "ErrorMessage": "No Operation Master Detail found for this Operation.",
  "ErrorType": "Ice.BLException",
  "ErrorDetails": [
    {
      "Message": "No Operation Master Detail found for this Operation.",
      "Type": "Error",
      "Table": "QuoteOpr",
      "Field": "OpCode",
      "Program": "Erp.Services.BO.QuoteAsm.dll",
      "Method": "GetOprOpCodeInfo",
      "ColumnNumber": 17,
      "LineNumber": 18143
    }
  ]
}

Ended up being the default site issue that it seems everyone comes up against.