I know I am supposed to get e-mails everytime that someone replies to an answer I marked as favorite, but I just don't. Is there any setting I'm missing? Did I misunderstand something? Thanks!
When a favorited question is updated (via a new comment or a new answer), the count on the dropdown at the top of the screen is updated.
So if anything new was added on that day, week, or month, respectively, the count is incremented.
It is shown on your profile as well, but this counts the number since you've selected that tab last:
I'm not aware of any other notifications on favorites, in the Collider or otherwise.