Welp. As of Sonoma 14.6.x calling applicationMusicPlayer crashes the Music app. Using systemMusicPlayer was the only choice for my music player until upgrading to Sonoma, and now I must return to it again. So weird…

Yeah, I posted about it on Stack Overflow when I was stuck like you, and then answered my own question, including the code snippet I used. No weird side effects, the overhead is negligible, just have to remember you can’t control play/pause in Music while your app is in use. Glad you were able to get a fix from it, too!

Just came across this post. I had this issue when I converted my iOS jukebox app to Mac Catalyst last year. I also discovered that changing the playback state would update playback time, so I added a play() command that is triggered in my one second Timer, and that solved my problem!