After just encountering this issue I have found a solution. I had the profile sync error for about an hour but finally figured out how to fix it.
Steps:
Hard reset your Xbox one checking your account after each reset to see if it is fixed.
Go into system settings and disconnect from wifi then reconnect.
Repeat first step but pull out Xbox by the plug and wait 5 mins until you reconnect the plug. Then check your game after doing so and it should be fully synced up to your profile. (If not connected just reapeat).
I found my solution finally. I am in th UK and use Sky BROADBAND… And on this occasion I must apologise to 343. SKY BROADBAND SHEILD!! Turned itself on a week ago. I didn’t ask it to. I imagine it’s the same story for hundreds of players here in the U.K. at the moment. Turn off your Sky BROADBAND sheild! I realised it was also blocking halo waypoint from my phone when I was connected to my wi-fi, but I could access it with 4g, so I realised my internet had to be blocking specifically halo based internet stuff… which therefore blocked my profile from synching. Very annoying. But once again. Apologies to 343. Still received no help from them though… lol.
I just had a look at their web site and it looks like sky broadband is in bed with McAfee … that explains a lot.
McAfee has a history of over blocking and even corrupting client devices (DAT 5958 disaster).
This is a great example how 343/-Yoink!- could improve troubleshooting by offering more diagnostic data than this very generic “Profile Sync Error”.
The Xbox itself could write a file with transaction results - and there you would probably notice lots of sent request to xyz that never received a response. And with that information you then could further investigate.
Does your sky broadband shield offer a log that identifies the actual host that was blocked (maybe even with a port number)?