AVPlayer fails, requires iOS (10.3.3) restart

I am using PHImageManager:requestPlayerItemForVideo... to load AVPlayerItems, and play in an AVPlayerView. I typically have 3 items loaded at once, one displayed and next/previous on deck for PagingScrollView (but not playing). Occassionally, video playout fails, with AVPlayerItem saying "decoder is not ready". The only way I can fix it is the restart the device. It appears that something my app is doing is permanently disabling members of the system wide AVPlayer pool. Has anyone else encountered this?