Hello again,
We have now made some progress with this and can report that the problem affects certain albums only. An example is Led Zeppelin || by Led Zeppelin. I have reported this to Discogs and am awaiting their response.
We can actually work around this, and since Discogs don't seem to be making much headway we will probably do so in the next version. We can't release anything immediately, but if there's no news from Discogs we will provide a beta with this fix included as soon as we can.
In the meantime, the lookup should work with the majority of albums. If anybody finds one which fails, please post details here and try to get a track listing and album cover from Music Brainz or tracktype.org (there are no album covers available from the latter). The Amazon databases contain a lot of noise, have no track times and are really only useful for album covers.