Update:
First of all as others said above me, players who experienced the sync issue did not get any sort of compensation when the patch rolled out; and at this point I honestly believe never will.
I've come back to the game but while I was at it, I spent my first hours trying to replicate the issue before even thinking of grinding again, just to figure out a workaround and hopefully save a painful experience for myself and everyone else.
After some testing and multiple account resets due to the error, I've come to the conclusion that hitting either "Play Online" or "Play Solo" while your character and car aren't fully loaded, drastically increases the chances of experiencing the sync error. I say increase chances because you can still experience the error while they are fully loaded, but that would be due to your own network issues and is indeed an extremely rare occurrence.
If you want to keep playing the game and do not wish to get your progress reset, I honestly suggest allowing the game to fully load your character, car and wrap before hitting any play button, especially when switching from solo to online or vice versa, since that's when the error happens the most.
Happy grinding and happy holidays!