taglib# returns wrong duration

I'm getting the duration of an MP3 file in this way:

TagLib.File file = TagLib.File.Create(fileName);
var duration = file.Properties.Duration;

and it is consistently giving me a duration between 68 and 75% of the real duration. Windows File Manager, VLC and just playing the MP3 and measuring with a stopwatch agree on the other duration.

Any ideas what's wrong here?

Turned out to be a bug: https://bugzilla.gnome.org/show_bug.cgi?id=605765