Sometimes it takes a while to show up. I wouldn't be able to tell you the official reason why, but I've had times when it wouldn't show up for an hour or so. There are a few things you could try: restarting Impulse a few times, hitting F5 in Impulse a few times (refresh), clicking the Impulse orb in the top left and "Check for updates..", Impulse Orb and reset data. Of those, reset data is most likely to work, but it can take a little bit.
Other than that, just wait and it will show eventually.