Can a custom Inspector serialize a List<> of derived classes?

I'm creating a custom inspector for one of the monobehaviour components in my game.

This class stores a List of behaviors that derive from a base behavior. These behaviors are marked serializable, and the custom editor is wired up to show the list of these derived behaviors and their custom properties (via reflection) that each behavior exposes.

Example:

List with these in the list: NPCWanderBehavior NPCMoveToBehavior NPCIdleBehaviour

The inspector shows each subclass with their properties, and modifying them seems to save those values (at least ,when I set the values on them, and I switch between nodes or run the game, those values persist). The problem is that when I save the scene, exit, and restart, those values are gone and the list only has the base class for these as serialized.

So if I have this list of commands:

NPCWanderBehavior NPCMoveToBehavior NPCIdleBehaviour

added to a game object component in the scene through my custom editor, when I save and reload my list is:

NPCCommandBase NPCCommandBase NPCCommandBase

So it looks like even though all the classes are marked serializable, that when saved only the base class is serialized, none of the subclasses.

Is there a solution to this? The custom inspector would go a LONG way to managing the command list for the level designer, and it would be quite elegant if I could get this to work.