Cannot update mutability of an attribute

Questions API
1

Hello,
According to the SCIM RFC, certain fields can be set to “immutable”, “read_only”, “read_write” and so on.
Apparently that is supported in Okta through the API

but when I try to actually use it to update an attribute that has a “READ_WRITE” mutability (I can’t do that via UI).

mutability:

string
Defines the mutability of the property

Enum: "IMMUTABLE" "READ_ONLY" "READ_WRITE" "WRITE_ONLY"

But, when I do that, nothing gets changed (and mutability property is not even returned). All other fields (like title I have no issue updating via API).

Looks like either a bug or incomplete documentation.

I’m using this app

Example request:

POST https://{yourOktaDomain}/api/v1/meta/schemas/apps/{appId}/default
{
    "definitions": {
        "custom": {
            "id": "#custom",
            "type": "object",
            "properties": {  
                "myProp": {
                    "title": "myProp",
                    "description": "my prop",
                    "type": "string",
                    "externalName": "extProp",
                    "externalNamespace": "urn:ietf:params:scim:schemas:custom:2.0:Ext",
                    "scope": "SELF",
                    "master": {
                        "type": "PROFILE_MASTER"
                    },
                    "mutability": "READ_ONLY"
                }
            },
            "required": []
        }
    }
}