Charlie, go into your User CP and make sure that you have the box for Subscribe to Threads checked. There has been some work done on the site and sometimes that bounces things around a bit. Let me know if you need any help and what you want done and I will see what I can do.
You're only given a little spark of madness. You mustn't lose it. Robin Williams Alix
I encountered that too, Charlie a few weekd back, and for some odd reason I found that if I set the notification (in my user CP) to "instant notification" I received the threads that I signed up for. But if I left it on "daily" as I'd always had it, they did not arrive to my inbox. Perhaps give that a try and see if it works for you too