If you change the type of an event dispatcher variable (why is this a thing?!), then you will permanently have a warning of the form "No delegate property found for NewEventDispatcher_0" that will be difficult if at all possible to remove.
Create an Actor blueprint
Add an Event Dispatcher
Change the variable type of the dispatcher to Boolean
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-63064 in the post.