It's almost like the system_health EE session has stopped collecting deadlock events on this particular server. The last one i have is 5 days ago. Meanwhile, with the trace flags set, I've had a couple each day in the SQL Error log, the latest was just a few hours ago.

I agree this is a major disappointment. Extended events are great, but if you aren't confident you're capturing all the info, they become useless. I might try to set up a separate EE session that only collects deadlock events, just to see what it does.

Have you opened a Connect case with Microsoft? If so, let me know the ID and I will +1. I'm having this issue on 2008R2. I wonder if it is still an issue in 2012.

Thanks

-Matt