Hi,
The Web Application Security counter shows 0 requests served on the dashboard. The other graphs and logs show that the requests are processing just fine.
I'm seeing the same behavior on the 8.200 soft release. In fact, since the WAF dashboard counter was first introduced, I've never seen anything besides 0 requests listed. I run Exchange 2010 ActiveSync and OWA through the reverse proxy, as well as a couple of regular web apps (e.g. the built-in web server for the EvoCam webcam product for Mac).