There are so many bugs after upgrading to 8.4, the one it bugs me a lot is the hidden cellular data usage. After upgrading to iOS 8.4 i noticed it uses lots more cellular data than before. And my data was empty before my bill cut off date. I have turned off Apple music, location service and background refresh. I thought it was my phone, so I wiped everything from my iphone 5s, did a hard reset and a clean install (not backup from iCloud). After that, the problem still exists, called my local provider and they said its a iOS 8.4 bug. Now, if i check in Settings > Cellular Data Usage > Current period it says 16.1MB (this is a lot since i only used whatsapp, text only, and Nike+ running app once) When i add up everything from "Use cellular data for:" it is 15 MB (including system services). So no idea where the 1.1 MB go. Anyone has this problem as well?