In iOS 9.3 and OS X 10.11.4, the behavior of forced subtitles in AVPlayer appears broken. During playback of a video having forced subtitles, the AVPlayer property appliesMediaSelectionCriteriaAutomatically is YES but calling AVPlayerItem's selectMediaOptionAutomaticallyInMediaSelectionGroup has no effect while it worked as expected prior to the latest OS releases. Likewise, the "Auto (Recommended)" option in the video players (QuickTime Player, Safari) has no effect.
When subtitles and/or closed captions are present in a video, QuickTime Player and the Safari video player present a CC menu which includes an "Auto (Recommended)" option. When "Auto (Recommended)" is selected, and the CC Accessibility options in the system settings are off, AVPlayer is supposed to display forced subtitles if forced subtitles are available for the current language system preference. This behavior is documented in the "Advice about subtitles" section of the AV Foundation Release Notes for iOS 5. This behavior can be seen by playing Apple's bipbop_16x9_variant.m3u8 on iOS prior to 9.3 and OS X prior to 10.11.4.
Am I missing a new system preference which hides forced subtitles, or is this behavior broken in iOS 9.3 / OS X 10.11.4?
BipBop:
https://devimages.apple.com.edgekey.net/streaming/examples/bipbop_16x9/bipbop_16x9_variant.m3u8
AV Foundation Release Notes for iOS 5: