Time goes slower in Makuri Islands

I ride Trainerroad workouts concurrently while Zwifting, and I noticed when I ride in Makuri Islands that the elapsed time in Zwift is 4 to 7 seconds slower per hour than the workout timer in TR. So a one hour workout ends at about 59:55. In all other worlds the timers match exactly.

Does this happen to anyone else? I'm running Zwift on a gen 1 Apple TV. Is it a hardware thing?