This all started when I added a new track to an existing playlist. I scrolled all the way to the bottom, selected it and then hit shuffle for it to move about the playlist from there. I’ve done this numerous times in the past and successfully, but this time after the first song played it would correctly continue to the next, but if I tried to go to the next track after that the button in the player was unavailable, the same control on the notification shade did nothing, and when on Bluetooth the button to skip track would only move the current track forward a few seconds. This behavior is reproducable for me every time and the function is immediately unavailable even when the initial song plays that is in the final position in a playlist. I know the last selection in a playlist should have this behavior, but I know in the past when I have hit the shuffle button everything worked fine since the Queue was fully populated.
Since this started happening, I presume since around the introduction of the ExoPlayer v2 because it is recent, I have also found that if I shuffle a playlist starting from any position after a few tracks the same thing will occur. At some point the Next track function will become grayed out even though the playlist queue is fully populated with subsequent selections.