BadChangeset Error

I recently noticed my Realm app was no longer syncing. Looking at the Atlas App Services showed a client token error that necessitated sync be terminated and restarted. Upon doing so, I’m now getting a BadChangeset Error;

Error:

failed to validate upload changesets: field "crop" in table "Farm" should have link type "objectId" but payload type is "Null" (ProtocolErrorCode=212)

This app has been in production more than a year, so this error is odd. In the client code, the crop property is marked as nullable. In the App Services schema, the crop property is not listed under the ‘required’ property and is defined as;

"crop": {
      "bsonType": "objectId"
    }

Within App Services, under App Settings, I’ve enabled the setting ‘Null Type Schema Validation’. This has not resolved the issue. How do you set a property as optional in the schema? Previously, if a property was not set in the schema’s ‘required’ property, it was presumed optional.

hmm odd - the option you flagged there should handle this case. - can you share the url to your app please and we will take a look on the backend?