My best guess is that he hit the end-of-line problem that so many encountered. It’s really a shame that the Clip Sport only accepts the old-fashioned CR+LF (DOS/Windows) end-of-lines. 
It’s quite unlikely that a regular user would even suspect this kind of “requirement” regarding playlists. Most people (who own and use a Mac or even a Linux PC) don’t even know about the various end-of-lines of text files.
Would it really be so hard to support all three EOLs (CR, CR+LF, LF)? :-o
