When you save something as a dynamic var, the only way to read it back is also through a dynamic var, since those variables are created in runtime, and (at least currently) I don’t keep track of the dynamic variables entered in editor time.
Now, specificaly for the agent override dropdown, I haven’t added the ability to select (type in) a dynamic var, mostly to avoid accidents, since a dynamic var is not really type safe. I could add that in the next version though 🙂
So, essentialy right now, an agent can be overriden only explicitely unfortuntately. Again, this is purely an Editor UI restriction.