Server Version#: 1.21.1.3766
Player Version#: 1.25.0.1511-47afccd4
When trying to add music to the queue, Plex adds it next in the queue instead of to to the end. This does not happen every time I use the functionality, but it happens often and has been occurring since I first started using Plex for music consistently this past spring.
When this behavior occurred today, I was in the middle of playing an album and then went to add a playlist to the queue. This occurs regardless of which track is playing in the album, unlike here. Likewise, I did notice that this happened when I added a playlist to the queue or an individual track.
I am guessing it is related to the fact that I played a single album from the start, but I will attempt to troubleshoot further and let you know.
EDIT
I am certain that at some point I have been able to use Add to Queue properly in some contexts, but as it stands I have tried starting a playlist by hitting the play button in the top right hand corner, hitting play on the first track, or just hitting the shuffle button–yet when I go to add a song to the queue after the music has started playing it adds it to the #2 slot.
EDIT 2
To completely contradict what I said in the initial post, I am now only able to reproduce the issue if I hit play on a playlist and then try to add another playlist to the queue. If I play an album and add a playlist to the queue, it appears to work, even if I skip the first track or let it finish.