If this works in rhythmbox then it's potentially an empathy problem. If it doesn't work, then this is either a xmonad or gtkstatusicon problem. Since pidgin doesn't use gtkstatusicon while empathy and rhythmbox do.
If this works in rhythmbox then it's potentially an empathy problem. If it doesn't work, then this is either a xmonad or gtkstatusicon problem. Since pidgin doesn't use gtkstatusicon while empathy and rhythmbox do.