Fedora, by default, sets up it's disk using Linux Logical Volume Manager. However, Debian-based (and by default Ubuntu derivatives) distros does not install the Logical Volume Manager package by default.
You must install and setup the package before GRUB will recognize the volume that Fedora is installed on.
sudo apt-get install lvm2
Fedora should then be listed on GRUB's menu items.
Hope it helps.