I have a '10 Focus SE I got used about three months ago. I updated the Sync software to the then-current version. I connect my iPhone for both phone and music via BlueTooth.
Every now and then, with no pattern I can determine, when I get into the car and turn it on, the music system immediately plays the FM radio instead of connecting to my phone and playing the music where it left off when I last got out of the car.
I am turning BlueTooth on on the iPhone before I get in the car, and I’m turning it off after I turn off the car and exit it, so it’s not a matter of BT from the phone not being available.