One thing I've found to be an issue with Akamai and an F5 in the mix is Akamai holds connections open for a while. When you make a change to an iRule the change only happens on new connections coming in, and since Akamai is holding connections open for 20 or 30 minutes, you make change after change and don't realize it's not getting applied to the traffic that you're testing.
Unless Akamai has some type of redirect in it, I'd expect that's what you're seeing. If you have access to Akamai, I believe you can clear the connections somehow after you make your changes.