you have right sry… missed that is a blueprintimplementableEvent 
I said then wrong…
So the first problem with that… BlueprintImplementableEvents must be overrided in Blueprint!
This is why we call them BlueprintImplementableEvents…
You cant override them… in C++! If you want override in c++ … so you wanna do things both in c++ code and blueprint code you shuld use BlueprintNativeEvent
So you cant declare interface function as blueprintimplementableevent, then override as blueprintnative event…
That must be delcared as blueprintnativeevent and when you override you must override in this form:
virtual void Interact_Implementation() override;
Further Informations about interfaces and UFUNCTION marks: