Github issue 2869 was recently closed with an update to the nightly. However, the fix seems to be firing the events in the wrong controller. I created a codepen but I don’t think I can embed it (it’s anonymous) so here’s the link:
I use console.log to log all the events (before/after enter/leave) and it shows that they all (including leaves) fire from the controller associated with the tab you click on.
I posted a comment on GitHub but I don’t know if people get notified when a comment is posted to a closed issue or whether a new issue needs to be opened.