The OnValueChanged attribute will successfully call a method, however Odin Inspector will not repaint the scene or game view afterwards. We have to click on or resize the editor windows to cause a refresh to occur.
To reproduce, create a string and set it's OnValueChanged attribute to a method that will update the visual component of a Unity UI text component to the latest text.
You can see that the OnValueChanged method is being called, but the Unity Editor Scene & Game view are always one update behind, and for some other field types (such as color), you will never see the Scene or Game view update.
Using Unity 2017.4.1f1 and Odin 184.108.40.206.
Editor only mode is not enabled.
Experienced on a Windows 10 home edition PC.
To discuss further or request an example project, contact me at firstname.lastname@example.org.