change to prefab not noticed by collab

I am using Collab in Unity 2018.3.1f1 and am having problems getting prefab changes noticed by the system. For instance, if I have a simple character prefab with a NavMeshAgent on it, I cannot change the speed property and have Collab mark the prefab file as changed and needing to be committed. I can change the speed property and have characters in the scene update to the change, which is good and normal, but Collab never selects the prefab as something that changed. Is there a way I can force Collab to "check out" the prefab?

 

Of course, right after I wrote this, I saved the project, and the prefab change finally got noticed. This should be more automatic!