the track request, when including releases, used to show the tracknumber associated with each release. that information is now missing. see, e.g.: http://musicbrainz.org/ws/1/track/55a21d7b-22e6-4b4c-a9ec-46eb6d957433?type=xml&inc=releases. the website shows the tracknumber/trackcount (see http://musicbrainz.org/recording/55a21d7b-22e6-4b4c-a9ec-46eb6d957433 ) so the data is there but it's not where it used to be.