Had the same problem many have reported here. Sympoms were -

• Was able to load saved games fine on my "home" xbox but when I logged in to another xbox I got the good old syncing your data message until the sync eventually timed out or I gave up
• Even on a "home" console, if you get an error indicating that the local game saves and the saves in the cloud are mismatched, you get the same endless sync behavior. Once you get this behavior it doesn't go away.
• Sometimes the sync gets a certain percentage through and sometimes it doesn't but in all cases the console becomes laggy and sometimes crashes

I tried all of the posted workaround having to do with disabling the network/starting the game not logged in, tethering the console to a 4G network, reinstalling the game, removing MAC Filtering, etc, etc. None of it worked.

Due to the way the console was behaving and the locking up, I suspected that there was a memory leak caused when there were too many saved files to catalog and sync. Sure enough, I had like 30 save files and my son who was also having the problem on a different xbox had 50. By deleting the most of old saved files, I was able to get both of our consoles to sync FO4.

Here is what you need to do -

1 - Boot the console and login. Launch FO4

2 - As soon as it starts to Sync, hit cancel

3 - The system might grind for a while (the longer the sync has been running or the more saved games you have the longer it seems to take) but eventually you will come to the menu. Select Load from the menu

4 - Scroll down your list of games and start deleting the saved games one at a time. I left 5 of the most recent saves.

5 - Cancel out and hard reboot the Xbox

6 - Login and launch FO and your sync should work. It might take a while but it will sync.

Like I said, this worked 100% of the time for me.

I would not recommend going to the "Manage This Game" app and deleting all of your local saves. This will cause all of the saves to be resynced when what we are after is to lessen the amount of data that is synced be deleting specific saves and flagging them not to be synced.

Hope this helps.

I'm going to give this a try.

Out of curiosity, when this synching is happening are we uploading local saves to the cloud, or downloading cloud saves to the console?

It seems like it must be downloading, since my saves appear to cease to exist on the console unless I synch...but then this fix wouldn't make sense.

Edit: Well, this didn't work for me. It was worth a shot.

I think that it's doing both. It has to determine which save files it has and which it doesn't. Then it moves them back and forth to get both versions in parity. I'm guessing that the FO saves are big top so just moving the data around is a killer.

Let me know how it works. Good luck.

No dice. It was worth a shot. Thanks for writing it up. Guess it's time to nuke and pave...again. Maybe this third time I'll make it past level twenty-five. So frustrating.

Cheers

Crap. Good luck man.

Hey out of curiosity did it sync any data back down? So if you stop the sync and try to load a local file, are there saves there that weren't there when you cleaned up?