So, after quite some debugging with the songs from the other user, I have identified a bug. This problem that you also have is caused by using Autoplay in a playlist with songs that have different sample rates. In certain constellations the timing is off when scheduling the next song and therefore you see this negative countdown timer.
I think I have fixed the issue now and this fix will be available next week in version 3.5.0. Until then, make sure all songs in a autoplay playlist have the same sample rate or avoid using autoplay.