Same problem here in case of waking up with an external display connected over Thunderbolt <-> Displayport adapter. I will add to that that not only does the process hang but the MacBook is overheating, the fans are running full blast and Activity Monitor doesn't show any process consuming too much CPU power - actually Activity Monitor is the most CPU-consuming process. If I kill com.apple.hiservices-xpcservice then CPU goes back to normal.

Have you found a solution for this?

I'm using Xamarin.iOS with Xcode 12 and it works for me fine: 1) set automaticallyWaitsToMinimizeStalling = false 2) set preferredForwardBufferDuration = 10 (seconds) 3) play() The player is really buffering till 9.7 - 9.9 seconds, that's great! What's not great is that playback does not start automatically. I needed to add an if myself: 4) calculate the total buffered time from player.currentItem.loadedTimeRages 5) if the total buffered time 9 seconds the run the player by playImmediatelyAtRate(1)