I have had my Lumia 920 for almost a year now and I haven't had any data problems until after I downloaded the developer GDR3 update. I haven't changed anything in my settings or been using the internet too much and I only have three apps able to be used in background data: Instagram BETA, Horoscope, and LockMix. Yet, it shows that I have been using almost double the data I usually use by this time in my bill cycle. Does anybody know why this is happening?