Recently it seems sometimes fuelly will not calculate L/100 km (probably same is true for mpg) for a fill-up. Sometimes going to the entry and updating it will trigger fuelly to do the calculation, but often it will not. All other data seems correct, just no fuel economy for the fill-up.
I looked at your data for the fuelup in question, and you have it marked as a partial fillup. No mileage calculation is done on fillups marked as partial, as the exact fuel to go the distance logged is not known. This data is used in the overall mileage statistics for the vehicle though. If you had marked this fillup as a partial on accident, you can go back and edit it. Everything appears to be functioning normally as far as the site is concerned though.