Subsonic & Panasonic TV DNLA

[quatermass]

Got myself a Panasonic TX-50CX802B which claims to be able to DNLA.
It's internal app found Subsonic 6 (perimum) easy enough on my LAN and listed the various folders. But on selecting a mp3 file it claims it can't read it. I tried others and same result.
Tried some MP4 files and same result.

Any clues on how to proceed?
Panasonic is up to date, Subsonic server (Windows 10 Pro x64) is up to date and working just fine with Dsub android app.

Thanks.