So I've had this issue since Saturday 16th November when my game crashed on PS4 and at first it was only the error where u can't join an online session but then it became the item sync error.
I tried many different ways to fix it including some suggestions on this forum but nothing. I've managed to get the game working and I am able to play online now but there's a catch.
In order to play again like normal you need to have a savegame file of progress before you got the error, I luckily had one in my online storage. I loaded that file up and got the prompt where it says "file doesn't match our inventory" blaa blaa and I just hit yes then it synced with no issue.
So if anyone has an old save before the error I'd suggest trying it, might work for you. Good Luck, also keep your corrupt savefile safe too if you want to go back to that in future after the patch.
