Why did my Apple Music playlist disappear after syncing with my iPhone?

I recently spent several hours carefully curating a very specific playlist on my computer, only to have all the songs disappear when I tried to sync it to my iPhone. I’m genuinely confused as to what went wrong, and quite frustrated that this happened. The playlist appears empty now on both devices–is there any way to recover the songs that should be there?

I’m currently using the Apple Music free trial, and while I wanted to give it a fair shot, this experience has been pretty discouraging. With Spotify, my playlists sync seamlessly across all devices without needing to navigate a maze of settings or manual steps. I had hoped for a similarly smooth experience here. I want to like Apple Music, but it feels unnecessarily complicated and unreliable.

[Re-Titled by Moderator]