Originally Posted by
chan1108
When I searched on Turkish Airlines’ website, I noticed that BOS-IST-HKG flights in Q-Q class earn only 4970 miles. However, the actual great circle distance is 9814 miles and the earning rate for Q class is 100%. Could the 4970 miles be a bug? If I actually book a flight that shows 4970 miles, will I only earn that amount, or will I still receive the full 9814 miles?

Yes, it is a bug. It happens often, at least on the routes I fly.
When I noticed this I was initially worried too, but contacted TK and they confirmed the quoted mileage accrual was incorrect. My flight did earn according to the booking class.