Note: as TWG wrote WAV had only very basic tag possibilities. Recently this has changed though.Hence for something the cost of the Beosound/Beomaster 5, this kind of basic functionality would have been expected as a minimum, especially considering that with the Beomaster 5, it's basically a Windows PC.
So with the basic settings of the BS5 maybe the tags are not read completely (the BS5 works on Windows XP Embedded).
I can not check the functionallities any more because I sold my BS5 before Microsoft reported the end of support for XP Embedded.
On my Beosound 5 Encore though all tags data are shown, also from WAV files.
You should try 3 things:
1. Switch on Twonky (which comes with a BS5, but in default not on), see what happens if you use this music server
2. Convert some WAV to FLAC or WMA lossless (if the WAV is tagged, the converted files will have the tag data also; at least using the proposed converter program) and rescan the content of the BS5. The converted files should be vissible.
3. Install a dlna/upnp server on your Mac/PC. Let this server scan the directories with the WAV. Setup the BS5 to read this music server (I'm convinced the WAV tag data will be shown)