Description of problem: Not sure which component to fill this bug against as multiple applications are affected so it should probably be filled against some library instead (gstreamer, taglib?). Anyway, in Fedora 19, some GNOME applications no longer read APEv2 tags from MPC files. For example, choosing properties on an MPC file and Audio tab shows fields such as Artist, Album etc as Unknown. Rhythmbox also does not recognize tags in those files. It used to work in earlier versions of Fedora and at around Alpha/Beta of F19 - I don't remember exactly when it stopped working. Other application like Decibel, Exaile, Clementine and EasyTag do recognize those tags properly but I guess they are using some other library to read them. I have gstreamer-plugins-* and gstreamer1-plugins-* as well as taglib-extras installed on my system and up to date.
It seems to be working fine in F20 beta.