The error specifically occurs when a track Apple Music is shorter than 60 seconds, finishing playback, do not jump to the next topic, so the next song on an album or playlist is not played and appears to be in a perpetual state of buffering.
It seems the problem lies in the streaming process, when the current song is finished soon and iTunes puts the next track in the queue to begin downloading for later playback after the current track ends.
However, when the song is less than a minute from the end, downloading the next song does not start, apparently because iTunes does not recognize files less than 60 seconds long to make a buffering of the next track.
The ruling only affects tracks transmitted through the service Apple Music, with songs and albums that were stored locally on iTunes. The bug could not be played on a Mac running the beta of macOS Sierra, or on an iPhone with iOS 9.3.2.
The error has been reported to Apple and is expected to be resolved in a future update of iTunes.
Once again put on veil Apple's ability to detect errors in the constant updates of its main programs, in this case iTunes, whose previous revisions also contained important bugs, as happened a month ago with the removal of hosted music files locally on a Mac.