Amarok does not display the "Album Artist" tag for some files (even if I rescan the collection and even if I remove ~/.kde4/share/apps/amarok). The field is shown as empty. Other software, however, does display the tag (like kid3 or MusicBrainz Picard).

Every time I scan the collection I get a message when it's done that complains about some duplicate UIDs.

Thanks for your time.

UPDATE: An odd thing I found out is that while I cannot add the "Album Artist" tag manually in Amarok, the MusicBrainz feature of Amarok can. And once MusicBrainz adds the tag, I can edit it with Amarok manually. But Amarok still won't detect any changes made by other software.

Does Amarok have a database it fills with collection information? How can I clear it?

Odd. What version of Amarok are you using? Your profile displays Arch, so I presume that is your distro.

Have you checked permissions on those files? You should be able to edit any field that's displayed.