When working with CPP+BP interfaces, avoid using Cast and avoid calling interface functions directly.
For testing interface, use
if (HitActor->Implements<UInteract_Interface>())
{
//...
}
Store only the AActor* (or UObject*) in a variable, you don’t need a pointer to the interface.
When calling interface function, use
IInteract_Interface::Execute_ShowInteractionPrompt(HitActor);
IInteract_Interface::Execute_Interact(CurrentInteractableActor);