I've had this issue happen twice and both times on my Razr MAXX HD. My phone will be connected to WiFi just fine, but if I go into Google Play Music, Movies & TV, or YouTube it will not show the Chromecast button. The weird thing is if I go into Netflix the button shows up and will cast just fine. When this occurs I can go into the same apps on my Nexus 7 and they all show the chromecast button. If I reboot my phone it will start working. It seems almost like a process is failing that only affects the Google apps. Does anybody know what this might be so I could just restart the process instead of having to reboot my whole phone when this happens?