Google Drive Backup doesn't work if there are no fill-ups added yet (Error ID#20)

When we add new car and add some costs to it, whenever Fuelio tries to sync newly added costs with Google Drive, it results in error notification saying "Error ID#20" and backup is not created. Additionally, the cost list seems empty for the car (saying that there are no costs for this car yet), but after clicking on "Costs" we can see all the costs that we have added. Both issues are automatically fixed when we add the first fill-up to that car.