Label for "Related" Case is blank

If I add a Case as a "Related Item", the title does not show up in the list; there is just a blank space with the " - " at the right-hand side. The link works if I click on the space where the title should be, it is just that the title is blank.

This seems only to be an issue with "Case", and doesn't happen for other document types I've tested, e.g, if I add a Web Page or Newspaper Article, the title shows up in the Related list as it should.
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