Author name not appearing on commit if over specific length

A username (author) name above a specific length is not displayed on the "Commits" page beside that person's commit details. The "author" column is left blank.
One of the users has a name 25 characters long and this is no longer displayed. It is not even truncated either, it is just blank. A user name of 14 is displayed in full.
However, if the commit details are examined (i.e. drilled into) the author name appears correctly on this page.