Cannot use realm.add with an AsymetricObject

I have a model that I want to add as an Asymetric Object.

I declare it as

class _MyModel {
  late ObjectId id;

When I write the code to attempt to write it…
await realm.writeAsync(() => realm.add(myObject));

… I get a compiler error…

MyModel' doesn't conform to the bound 'RealmObject' of the type parameter 'T'.
Try using a type that is or is a subclass of 'RealmObject'.

When I look at the .g.dart file for the model I see that it is (correctly I think) generated as an AsymetricObject and not a RealmObject.

class MyModel extends _RealmFileRecordLinkChunk
    with RealmEntity, RealmObjectBase, AsymmetricObject {

Models that I do not have marked as asymmetric have RealmObject instead of AsymmetricObject.

The .NET client works great w/ AsymmetricObjects… what’s up w/ the Dart SDK?