I’ve been having the same problem.
Back when they had the latest update after installing it, my phone would no longer ring if I had Facebook open.
It also stopped my phone from syncing to my car so I am no longer able to use my hands-free when I am driving, and people are constantly saying that I am breaking up when I use speaker phone. Over 2+ week period I Spent approximately 25 hours with one Apple tech person going over every single thing they could think of. They had me download files that they sent to me and install them on my phone that would track what the system of my phone was doing while I was using it. They accessed my phone remotely multiple times running a number of tests. The logs that they compiled that were being recorded when I would use my phone they sent to their engineers and even the engineers couldn’t give any answers. They ultimately sent me to an Apple store where they checked out my phone and also could not give any answers. Nobody seems to know what the problem is.
Now on top of all this the screen of my phone has been constantly freezing up over the last two weeks. It’s not just an app where I can close the app and reopen it, but it’s the entire phone. I can’t power it off to restart it or anything. I just have to sit and wait and eventually it will unfreeze.
I’m so angry and frustrated with Apple. I spent $1200 to buy this new phone right before the new update was downloaded and it screwed it all up.
Ive been a loyal iPhone user, but this may be my last Apple product unless they do something about it soon.