This project uses "wait" blocks to sync with the music, but you might want to double-click the green flag anyway. Just to be sure™.
Credit to the authors of the topics shown in the project, both for bringing this bug to the Scratch Team's attention, and for having to experience it themselves. Fun(?) fact: One of my projects was affected by this bug yesterday; specifically, the Vector Cosmicat project lost three costumes, and I had to recreate them again. Thankfully, none of the main vector costumes got lost, so I was mostly able to get away with just copying assets over. Other people weren't so lucky; they're still affected by this bug at this very moment. For future reference, here's what my signature looks like right now: https://u.cubeupload.com/CocoTheMii/screenshotscratchmit.png
