Duplicated listener BP fails to bind and respond to events

I am wondering whether anyone can explain this. I have two Blueprints classes, one of which (the listener) binds events to the other in BeginPlay and then responds to the events generated by the other class as required. The class I bind the events to is stored as a variable in the listener BP which I set in the editor. This all works fine.
When I went and duplicated the two classes (using <ALT> and the move tool), and set the BP variable to the new BP the events failed to be called in the listener BP. I eventually deleted the duplicated listener BP and dragged a fresh copy in from the browser, set the BP variable - and all was working again.
I am assuming UE4 is creating an instanced class when the original is duplicated, which prevents it from binding to the new BP and responding to events. Can anyone confirm this?

It should work fine after a drag copy. Maybe you need to check your steps…

It seems it is connected to Sequencer somehow. I am using the BP’s in a Sequencer shot and when I edited the shot the listener BP stopped working again. After editing the shot it magically started working again. It seems strange that sequencer has the power to decouple events like that though.