Idk if it's for only SteamOS or every version of Linux, but dragging the .mid file into the Minecraft window does absolutely nothing

So I dragged the midi file into the .jar file itself and it worked lmao

It's tested on Manjaro Linux, KDE. Please share the latest.log after you dragged and dropped, and the midi file tested.

Had the same issue on Ubuntu 24.04, latest.log said:

[21:16:37] [Render thread/ERROR]: java.io.FileNotFoundException: /home/user/midis/Focus.mid (No such file or directory)

I was able to work-around the problem by moving the midi files to a data directory inside the instance (e.g. /home/user/.var/app/org.prismlauncher.PrismLauncher/data/PrismLauncher/instances/myworld/minecraft/midis)
then dragged those files to the song list :)

I improved error messaging, but I don't think I can fix this issue itself. Based on your description, I assume it's a permission issue (like you can't drop files into blockbench when run via flatpak without whitelisting the source dir first.)

@kjhf if you used flatpak, can you verify this please? E.g.:

flatpak override org.prismlauncher.PrismLauncher --filesystem=host

Or more securely

flatpak override org.prismlauncher.PrismLauncher --filesystem=$HOME/midis