If it's a live song (ie: where a person is drumming rather than a synthesiser or computer keeping the beat) then it won't have a steady bpm and the usual bpm finders won't be able to get a bpm for you.
With live songs, you usually have to alter the bpm every few beats or so in order to keep it on beat. Otherwise, using songs that don't have live drumming in them
If it's not a live song, then I have no idea what the problem is
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Well, it explains the disappearance