I pushed out an update (1.1.2) that should address the problem: https://tizian.itch.io/playdate-music-box/devlog/647665/bugfix-release-112
(In case you’re curious, the reason behind it was related to the Playdate’s internal file system: https://devforum.play.date/t/asset-filenames-ending-in-non-alpha-char-before-extension-work-in-simulator-but-fail-on-device/11777/10)
Thanks again for reporting!