MP3 "disc number" tag ignored

I'm running Serviio 0.6.0.1 on Linux, serving my music collection to a Sony BDP-S370 (I think!) BluRay player. It works fine, except that the "disc number" tag seems to be ignored.

I have a number of multi disc compilation CDs tagged (MP3 ID3 v2.3) as follows:
Disc 1 / Track 1 ...
Disc 1 / Track 2 ...
...
Disc 1 / Track n1 ...
Disc 2 / Track 1 ...
Disc 2 / Track 2 ...
...
Disc 2 / Track n2 ...
Disc 3 / Track 1 ...
Disc 3 / Track 2 ...
...
Disc 3 / Track n3 ...

However, the browse order displayed by the Sony for these is all the track 1's, followed by all the track 2's, track 3's, etc. It's sorted by track number (then I think track name) and disc number is ignored.

I couldn't find this problem mentioned in the forums or bugtracker. Anyone else seeing it?

[zip]

Disc number is not stored in the database so you'd see this behaviour.