I logged a call with the JetPack support team over the weekend and they tell me they’re looking into the issue now (“We’re investigating this issue, and will get back to you once we have an update.”). I have exactly the same problem with 1.8.2, that’s resolved by using 1.7.
Subscription notification emails and confirmation of subscription is going out, but no notification of new posts after subscription. No notification of comments either!
