Thanks for doing this. I filled it out. It’s happened to me the most while using the AI Toolkit library as well as my own custom weapon classes. In the case of the AI all of the placed actors which were children of the shooter AI character had all their attributes reset. Lost 4 days of work 
For my weapons I had a bunch of custom variables for VR grip related stuff that was reset. Really frustrating and makes me really not trust the Unreal Engine. Aside from that I really love working with Unreal.
Edit: Also wanted to add what is very reliable but I thought was by design or stupid design is if I ever change a default value on the parent blueprint it will reset any overrides on the children whether you wanted it to or not.