I think something is up with my account. I just got a new car and have the setting for fuel-ups set to odometer (not tripmeter). I have entered all the information required for my first 2 fuel-ups, but Fuelly still says 0.0 MPG. I did not click the "I missed a fuel-up" box either.
I've used Fuelly for years with my old SUV so I don't think it's user error.
We prefer not to delete threads like this. Someone else will have the same question in the future, and they can get an instant answer by searching and finding this thread instead of posting and having to wait for someone to reply. That's how forums work.
Actually, Fuelly requires the 3 fuel-ups for the vehicle to be publicly visible/searchable from the Browse Vehicle's section.
It is true that the first fuel-up is 'skipped/ignored' when tracking via Odometer, but your second being skipped through a red-flag for me.
Taking a look at your log, I found the error- http://www.fuelly.com/driver/mantruck101/xc60/log
Odometer - 131,882
Odometer - 13,558
Unless you're secretly Doc Brown, I think you may have missed a digit there on the 14th.