It’s not that you cannot. It’s the way you attempted it. You can’t call functionality on an actor that has yet to exist… To call an interface there needs to be a valid instance of an actor first.
If you do call it for a null reference, nothing will happen because there is no implementation - that’s one of the more graceful things about interfaces. Try it with a direct reference and the editor will throw the now infamous Accessed None error.
An actor instance cannot spawn itself. One cannot be their own father. No time travel, please.
, even though this felt like a personal attack: