Symptom: Install appears successful, GRUB installed to either /dev/sdx or /dev/sdx1 - reboot results in "Operating System Not Found"
Cause: X120e BIOS (and possibly other Thinkpad BIOS') is buggy and does not handle GPT MBR information correctly. Attempted install with grub2-bios partition, EFI partition, etc. No dice.
Solution: Format your partition table to type msdos until a firmware update is released to solve the issue. Save yourself some headaches - don't use GPT in the interim.