Siri only works on WiFi after updating to 8.4
I have updated to 8.4 and I noticed that Siri only works when connected to WiFi. If I turn it off and only use my Cellular connection, it doesn't work. It's happening to my 5S and 6 plus. I tried resetting the network and Hard reset and still doesn't work. Is anyone having this same issue? I called my friend and he is also having the same issue. Ant comments is greatly appreciated. Thanks!
iPhone 6 Plus, iOS 8