Catch-22 for assignments with letter grades: You can't post a number score through OneRoster because there's a letter grading scale; you can't post a letter because OneRoster requires a number

We're unable to post scores for assignments that have letter grading scales. Has anyone else encountered this/have a workaround?

Steps to reproduce

• Enable a letter grading scale for an assignment (A+, A, A-, B+, etc.).
• Post a score for a student through OneRoster.
  
  PUT https://api.sky.blackbaud.com/afe-rostr/ims/oneroster/v1p1/results/3333333333333
  
  {
  "result": {
  "scoreStatus": "fully graded",
  "scoreDate": "2025-05-16T09:10:04Z",
  "score": 100,
  "comment": null,
  "lineItem": {
  "sourcedId": "1111111111111",
  "href": null,
  "type": "lineItem"
  },
  "student": {
  "sourcedId": "usr-2222-2222222",
  "href": null,
  "type": "user"
  },
  "sourcedId": "3333333333333",
  "status": "fully graded",
  "dateLastModified": "2025-05-16T14:55:02Z",
  "metadata": null
  }
  }

Expected result

• The score is posted.

Actual result

• Response:
  
  {
  "statusInfoSet": [
  {
  "imsx_codeMajor": "failure",
  "imsx_severity": "error",
  "imsx_operationRefIdentifier": "putResult",
  "imsx_description": "PutResult: LineItemHasGradingScale",
  "imsx_codeMinor": "invalid_data"
  }
  ]
  }
  

If we send a string letter grade, that also fails:

• PUT https://api.sky.blackbaud.com/afe-rostr/ims/oneroster/v1p1/results/3333333333333
  
  {
  "result": {
  "scoreStatus": "fully graded",
  "scoreDate": "2025-05-16T09:10:04Z",
  "score": "A+",
  "comment": null,
  "lineItem": {
  "sourcedId": "1111111111111",
  "href": null,
  "type": "lineItem"
  },
  "student": {
  "sourcedId": "usr-2222-2222222",
  "href": null,
  "type": "user"
  },
  "sourcedId": "3333333333333",
  "status": "fully graded",
  "dateLastModified": "2025-05-16T14:55:02Z",
  "metadata": null
  }
  }
  
• Response:
  
  {
  "statusInfoSet": [
  {
  "imsx_codeMajor": "failure",
  "imsx_severity": "error"
  }
  ]
  }