Realm Sync Rule is not working Properly

MongoDB Atlas App Services & Realm Atlas Device Sync
1

I am using the realm sync for the data integration. we have a different properties in collections that are not allowed to realm sdk to be updated. When realm sdk read the data. it gets that object value to null beacuse of new data enter in a certain field initially, after updating the data. Its value is set to null in our collection. For that issue, i have created the realm sync rule. But it is not working properly.
I am sharing the rule with all. please guide me where i am wrong. FrameSettings is marked as read-only but again its values are getting updating.

 "roles": [
    {
      "name": "owner",
      "apply_when": {
        "UserId": "%%user.id"
      },
      "insert": false,
      "delete": false,
      "search": true,
      "read": true,
      "fields": {
        "FrameSettings": {
          "write": false
        },
        "Status": {
          "write": true
        }
      },
      "additional_fields": {
        "write": false
      }
    }
  ]
2

This looks like it comes from Data Access / Rules in the Realm UI. Note that those rules aren’t used when deciding what data gets synced by Realm Sync - those are defined in the “Sync” section. Unfortunately, you can’t control which fields within a document/object can be synced.

3

@Andrew_Morgan thanks for the update.
Is there any way to restrict the field in updates? only allow one field in the update.
Can you share the documentation or example?