After a cold start (app wasn't in memory or was force closed), the previous song will play for a few seconds, and then seamlessly switch into the very first song of the playlist, at the same timestamp. After that, shuffle is broken: the songs play in order (which is, in my playlist, alphabetical sorting) until you fix shuffle by picking a track manually or switch playlists back & forth. Here's a video of the issue. Note that I am not triggering the first track switch: that's the bug. Th