If you want to access event/variable from your widget class, you can do something like this:
For your variable LoadingBP of type WIP Loading which i guess is a widget class. Represent a reference of a created instance of WIP Loading.
So for example you do Create Widget (WIP Loading) it will create a ref: WIP_Loading_0, you do this again, it will become WIP_Loading_1.
These instances are created ingame, that why you can’t select them from your default value. To access them, you need to set the variable when you create/spawn your bp class.