I'm using the last beta version available (2.80 beta 3 (May 20, 2016)) on a Motorola D3 (XT919).
I turn on the phone, open TC and play some mp3 songs. Everything's OK until that. Unfortunately, if I stop or pause the playing, few minutes or hours later I can't resume the playing, because the playlist simply erases itself. And, when I want to close the TC MediaPlayer on this scenario, it doesn't close.
I tried using the little x button on the right side of the pull down menu (it just doesn't respond). So, I tried opening TC MediaPlayer from the pull down menu, and press the big red X button. Aparently it closes, but the [play] button is still visible on the top of the screen, and I can launch it again from the pull down menu (and obviously appears without playlist).
I hope this helps to find a solution on TC MediaPlayer on missing its playlist after pausing/stopping for a while

Cheers!