When Perforce Revert Outside of Unity the Custom Inspector Isn't Updating?

I've got a project with Perforce as the version control provider, a serialized ScriptableObject with some primitives, and a custom inspector for that SerializedObject using only SerializedProperty's with serializedObject.Update() at the top of OnInspectorGUI() and serializedObject.ApplyModifiedProperties() at the bottom.

When I check out the SO, modify a value, then revert the SO from Unity, the modified value appropriately reverts to its previous value as expected. But if I had switched over to P4V (Perforce) and reverted the SO there, then switch back to Unity, the SO goes back to an unchecked out state, but the modified value still shows.

How do I get the modified value to revert when the revert happened outside of Unity? Clearly Unity recognized Perforce's revert, but didn't revert the serialized property.