Leclerc started only seventh after his crash in qualifying, and in a race not impacted by safety cars, he finished in the same position 52.9 seconds behind winner Red Bull's Max Verstappen.
His Ferrari team-mate Carlos Sainz fared little better on his run to fifth, having overcome a five-second penalty for speeding in the pitlane.
Leclerc said it was hard to predict the behaviour of the car not just over a stint but even within a lap.
“I was speaking just now with Carlos and what we are lacking is consistency from the car,” he said when asked by Autosport about his difficult afternoon.
“Not even from corner to corner, just in the same corner I can have a huge oversteery balance and then a huge understeery balance, and our car is so wind-effected.
“This year we have a car that is much more wind sensitive, and we are struggling much more with that. So there is a lot of work going on that.
“Other than that, for some reason this is off because it is not something I have had for the rest of the weekend so we’ll have to check the car, but I had a lot of bottoming especially in high speeds which is something I can’t quite explain, because I didn’t have that yesterday. So this we’ll have a look at in the data.”
Source: Autosport