Ok. Several things..
In UPNP the track meta data is supposed not to be passed in the media stream, but via the UPNP mechanisms instead. Either Browse() or Search() when pulling, or SetAVTransportURI when being pushed to.
However some renderers do also (or instead) extract the track meta data from the media stream too. The reason why this is often not a good idea is that meta data tags are often appended to the end of the file, which is ok if playing from a hard disk because the computer can seek to the tags instantaneously, however it is not ok when playing a linear media stream because by the time you get to the tags, the track playing is over...
When MC serves a track in Original form it passes the meta data in the above mentioned Browse, Search, or SetAVTransportURI calls and also embedded in the track stream. But when it serves in Transcoded form it only supplies the former and not the latter.
Furthermore Sony players are notoriously picky about the formatting of the meta data passed in Browse, Search, or SetAVTransportURI calls, and if it's not in the exact right format for them then they won't display it.
So if your player is not showing meta data then check three things..
1. Is the MC server set to play Original or Always Convert?
2. If Original then are your tags at the beginning of the file or the end? For FLAC or MP3 it is normally at the beginning, whereas for WAV or AIF it is usually at the end (and so too late to be any use).
3. In MC server settings Advanced, make sure that DLNA and DLNA extra are on. And if that does not work, also play around with the other Advanced server settings..
PS you may also have more success pushing to the player rather than having it browse and pull the tracks.