I forgot to say I already had synced Fuelio before, not sure when, maybe in January. I've changed Android and Fuelio versions since then.

I had the same problem. Pro 3.4.1, Nexus S, CM 11. I've removed my Google account then added it again. It asked for the permission once and I accepted. This didn't solve the problem.

Then, on my Drive, I've deleted the "Android" folder. Back on Fuelio, I've been able to sync it successfully.