Animation View Properties Disappearing

Hi! I am new to Unity and was hoping someone can help with an issue I am having with Animation View.

I am using the Unity Animation View to create a number of different animations for my 2D characters. I've already created around 25 animations, but noticed that the animation properties for some of these animations have disappeared (4 out of 25). I'll create the animation and it will be playing fine in game mode, then when I return to animation tab later to make an edit, the properties are all gone, but the animation file is still in mechanism.

Any suggestions on why this is happening and what I need to do to keep my animations from disappearing would be greatly appreciated!