Thanks to a user suggestion, we’ve added a “Watch a topic” feature. If you watch a topic (using the Watch button at the top of each topic) you’ll receive a notification whenever someone starts a new thread in that topic. If it doesn’t work for you make sure you have “Receive Watch Notifications” turned on in your User Preferences
Just to confirm, this should be working properly again now. Do post if not.
Would this be a good place to ask for an option of showing watched threads with new posts in the watched threads list first? Or for a clue.