[Si Coe]

Incorrect setup of the loop or wrong settings in the software mainly.

I managed to 'lose' peoples laps when we made a rather short track where the fastest drivers (but only a few drivers, and not every lap) were lapping under softwares minimum lap time. The program doesn't tell you its discounted the lap, it just ignores it so there was no indication there, all I knew was people were complaining. Its only when I realised that the minimum lap time had been raised for the previous meeting (on a long track) that I could solve the problem.
I'd call that one operator error as I hadn't adjusted the settings to the conditions.

Its not an insult to race controllers to admit that they are human and make occasional errors.....