Uhg, sorry about that. I'm not actually sure why your animations would get set back to "None"... wait, I why see now. The animationName field was changed to _animationName, and then a property named animationName was added. This is because the Inspector requires a field, but we actually need a property to control changing the animation name at runtime.
To fix it for you, you can rename the animationName property to something else, then rename the animationName field to animationName so when you open your project all your animations will not be set back to "None". Be sure to change "animationName" in SkeletonAnimationInspector to "animationName".