Departed around 2200.
The delay was due to getting a 3rd aircraft (777-300ER) crewed and waiting for an available aircraft. The 747 pilot situation is a little precarious at the moment so there weren't any standby crew to re-crew a replacement 747-400.
The same happened yesterday with a late substitution on the 263/262 RUH flight from a 747-400 to a short haul 767-300ER. Then the allocated aircraft went tech resulting in another delay while another SH 767 was brought out!
During other times of the year, passengers would be dispersed or smaller aircraft put on but as the flights are all so full, the flights must operate...even if it means incurring a huge delay.
Champ