OneRoster: Can't update line item category

Hi all, I'm getting an error when trying to change a line item's category. Is this by design, or am I doing something wrong here?

Steps To Reproduce:

• HTTP PUT lineItem_1.json to https://api.sky.blackbaud.com/afe-rostr/ims/oneroster/v1p1/lineItems/11122233334
• HTTP PUT lineItem_2.json to https://api.sky.blackbaud.com/afe-rostr/ims/oneroster/v1p1/lineItems/11122233334

The JSON files are attached above (highlighted). The only difference between them is the category IDs.

• lineItem_1.json has category ID lic-222-2222.
• lineItem_2.json has category ID lic-999-9999.

Expected Result:

• The first PUT is successful.
• The second PUT is successful. The assignment's category changes.

Actual Result:

• The first PUT is successful.
• The second PUT fails. An error message is returned:

{

"statusInfoSet": [

{

"imsx_codeMajor": "failure",

"imsx_severity": "error",

"imsx_operationRefIdentifier": "putLineItem",

"imsx_description": "CannotChangeCategory",

"imsx_codeMinor": "invalid_data"

}

]

}