I have this same problem. New iphone, completely battery managed per every Mac IT suggestion. Great battery life until this update. Usually needed a charge every 3 days or so ONLY, with same behaviors. No social media apps installed or anything pulling data on my phone, with the exception of manual mail and some texts. Did a test with a 100% charged phone at 5am. Put Netflix on for 2 hours - normally fine (usually doesn't touch much battery life at all). Drained from 100% to 35% in 2 HOURS. I saw the drain on the battery life section and it's dramatic drop. Sigh. Is there anything to do about this?