Tried flashing the latest AP1 CP and had no luck. Decided to start over but had to get back on t mobile,,, the first firmware. Flashed that, then att latest and then the nougat update. I also thought I'd skip wifi connectivity and went straight to data.
So far it seems to be working good (an hour out in the streets now and letting it do it's updates(this might take a while but I have data)). Im going to remember retrack to what I did that may have caused me to lose data and going to try disabling some att apps, connecting my gear s3, etc. (which may be the cause). Will let you know on my results.
Update: disabled att locker, att protect plus, att caller id, direct tv, hangouts, my att, setup and transfer, smart limits, uber, and lookout. So far so good. As soon as I get home going to try wifi calling.
I would recommend reflashing and not connecting to wifi and let the firmware settle in for those that don't have data.