QUOTE (gilbertasm @ Jul 19 2013, 01:54) <{POST_SNAPBACK}>
Well, foobar shows it as wavpack file and wvunpack can unpack it and produce wav file, so clearly this is a real Wavpack file.
As db1989 says, these are not actual WavPack files but archives that contain a WavPack file, and if the WavPack is not the last file in the archive then wvunpack will not be able to find the APEv2 tag (which is where the cuesheet would be).
The easiest way to find out (and actually the safest way to do anything with these files) is to rename them to just .iso and unarchive them into a folder. Then you can see exactly what's in there (the cuesheet may be a separate file in the archive) and wvunpack will be able to access the AVEv2 tag. If you, for example, try to edit the cuesheet or embed artwork in foobar, you can easily corrupt these .iso files (I believe someone doing this with .zip.wv files here).