#KDE's default #music player, Elisa is weird. You'd think if you double click an audio file, it'll open up with the default music player (Elisa), which it does - it'll start playing the music immediately but it doesn't.
It'd add the file to a queue instead. And the queue will be filled with other files you've double clicked and launch Elisa with in the (distant) past so probably the file you wanna play/listen to right now is ordered like 10th or god knows how many in the queue right now.