Most songs that I could find have the following set of formats available: AAC_160, AAC_320, MP4_128, MP4_128_DUAL, OGG_VORBIS_160, OGG_VORBIS_320, OGG_VORBIS_96, OTHER5

However, "I Write Sins Not Tragedies" by Panic! at the Disco (link), for some reason, doesn't have this set of formats: notably, it's missing all 3 Vorbis formats, leaving only AAC_160, AAC_320, MP4_128, MP4_128_DUAL, OTHER5.

Since librespot only tries playing the Vorbis formats, it will fail playing this song (in v0.1.6, it'd even panic here, but that seems to be fixed in the dev branch).

I haven't found another song that's missing Vorbis, not even on the same album. I'm not sure if the added effort to support a different format as fallback is worth it for what seems to be only one song (or, well, I would be very surprised if this was the only song with this quirk, but I haven't found any others yet).