pass child class to ScriptableObject.CreateInstance<> ?

I'm building a custom editor to assemble a list of custom scripts and put them in a List on a script deriving from MonoBehaviour.

So far, my editor is working well. The point I'm stuck at is passing a variable from a list of types to ScriptableObject.CreateInstance

code snippets:

     public class MyEditorClass: Editor
     {
     
         private List<Type> behaviorTypes = new List<Type>();
         private int selectedType;
         void OnEnable()
         {
              behaviorTypes = ReflectionVoodooThatGetsDesiredTypes(); // this works as expected
         }
     
         void OnInspectorGUI()
         {
               if (GUILayout.Button("Add", GUILayout.ExpandWidth(true)))
         {
                     AddStuff();
                 }
         }
 
         void AddStuff()
         {
             Type childClass = behaviorTypes[selectedType];
          AddBehavior(ScriptableObject.CreateInstance<childClass >()); // this doesn't work.  what is the proper way to do what I'm conceptually trying to achieve here? 
         }
     }
     

I have a base behavior class that inherits from ScritpableObject, and then several child classes that branch off of that to create a behavior tree. I have a List that stores all types that are derived from my base behavior class. I want to be able to select a type from that list and pass it to the ScriptableObject.CreateInstance() function.

I had this previously working using this line of code:

 AddBehavior(behaviors[typeSelection].GetConstructors()[0].Invoke(new object[0]) as BaseBehavior);

this worked, but due to serialization child class types were being lost. So, now that I've switched over to ScriptableObject, my serialization problems are solved, but instantiation problems arise.

Thanks in advance