I think I managed to reproduce the problem by engaging autoplay after the crossfade time has already been reached. So if my crossfade is set to 10 seconds. Engaging autoplay 5 seconds before the end of the song will cause this issue. Is that what happened?
Clearly a bug. A workaround would be to engage autoplay before the crossfade time is reached. Depending on your settings that could be up to 15 seconds before the end of the song.