Playlist keeps changing to next song even when I have repeat song enabled

When I play songs in a playlist on repeat song (aka repeat 1 mode, so supposedly I am looping on one song within a playlist), it keeps randomly jump to the next song when it ends.

For example, if I loop a song, it will loop for around 6-7 times, and then it jumps to the next song for no reason. Sometimes it just keeps going to the next song until the end of the playlist without caring the fact repeat song is still enabled.

This is a bug right?