Hello,
check the box inherited variables to see your parent’s variables, down the variable list. If you want them from a cast, you have them on typing them as others.
In your situation you maybe fail because you use a controller instead of a character blueprint which would be your enemy_master. You can check the actor type by using a print string for example to see what the other actor is. Then see if you are casting to the right actor. (Casting to parent works perfect for children)