No. The basic rule — applicable to all kinds of actors and all kinds of storage — is that actor-isolated storage can only be accessed from that actor. Stored properties on an actor instance are isolated to the actor by default, but that's just a default and is not somehow required for overall correctness. If you make a stored property on an actor instance and isolate it to a global actor, you've effectively made a little outpost of the global actor within the allocation of the actor instance. That actor has no special privileges to that storage and cannot touch it, so there's no reason to synchronize any changes to it with the actor.