Music doesn't Play in Loop in the Firefox Browser (haven't tested others), when the file is in the Music Folder.
The debug mode Shows, that the Loop is active and the file is playing, but the Sound stops after the first Play is completed.
Curiously, the Loops works correctly, when the Music file is placed in the Sound Folder instead.
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To me it seems, as if there is a bug in the Music Folder Attributes.