Just to add my own experience...
Upgraded to 5.8.1 yesterday and have been banging my head against the wall trying to figure out why I couldn't to see anything on the Alerts tab.
Came across this article and decided to try a different browser. And just like that all is right in the world. All data is now showing up.
The oddity is that I only use Firefox. Currently running 29.0.1
Now I can only see the alerts if I use IE 9 on Win7.
I would love to know why FF no longer works, but at least I now know there is nothing wrong with my vCOPs install.