Has anyone here tested Coinbase's Instant Payment Notifications lately?

I set up some stuff yesterday using the Coinbase API. They give you the option of creating a new receiving address, and adding a callback url, so when anyone sends a payment to that address, Coinbase's server is supposed to report it to the callback url. The callback is triggered immediately, at 0 confirmations.

My address and url show up correctly in their admin panel, but I was tailing my logs, and there was no hit to my server whatsoever when I sent payments to the address. I put in a support request 14 hours ago with no reply, and I just tested it again with no callback being triggered.

I found a support thread where people had this exact problem in late March and late April, the company only replied in late April saying oops, they had fixed it.

At this point, I can't really imagine using Coinbase for my application, because I would be constantly worried that it stopped working with no warning again, but it made me wonder: Are many people using this feature of Coinbase? Has anyone tested it lately to make sure it's notifying them? It'd stink to rely on their API and not even know this feature isn't working.