SYNC Reset

I have a 2015 Ford Fiesta which has Gen-1 SYNC installed. This is fairly basic but brilliant if you just want to use your mobile voice-activated and hands-free.
But a week or so ago, my moby became unpaired and just wouldn't pair back up again.
The Sync system was appearing to play ball and offering the 6-digit code which needed to be matched on my moby. My moby was finding SYNC but not (it seemed) the 6-digit code, and was therefore failing to pair up. So at this point it looked more like the problem was with the moby. But when I tried to pair my wife's moby it had the same problem. Also my moby was still able to pair successfully in my wife's car. So I then suspected my car. After numerous attempts at trying to vary the method (engine running, ignition on but engine off, etc etc) I then tried the master reset from the SYNC settinigs menu. But still no luck.
I was running out of options and contemplating the expense of having to go to a dealer for a software upgrade or module replacement, but as a last resort I disconnected and reconnected the car battery (left it unconnected for about a couple of minutes). And HEY PRESTO the pairing process now works fine again.
This post is mainly for info only in case others get the same problem, but I'd also be interested if anyone could suggest what gets reset by temporarily disconnecting the battery, but isn't reset by SYNC's own Master Reset feature.