There have been too many times where I'm working in the app builder, and my changes are not being saved along the way for me to publish. I have re-done so many validation settings, or changed field names, literally any change that I make, I've had to do them over and over, and refresh the builder to make sure the changes are saving as I go.
Very very slow and frustrating building process when it takes me forever to make changes, because I have to redo them again and again because the app builder isn't saving.