I just played now and gained a Rank. I quit using Start->Quit GTA Online to single player , got the spinny circle, everything normal.
I go back to online, nothing had saved. This is the first time I've seen this, I wasn't kicked, I quit, saving correctly. The Cloud appears fine, It just isn't saving.
I'm not sure what to do with this one, it simply isn't saving.
Saving is the most basic functionality you'd expect in an online game.