They left out a step, I am adding it here with my name next to it.
1.restart machine with Windows 8.1
2.determine "EFI System" parition with the Disk Management utility
3.run command prompt as administrator
4.type diskpart
PCIBUSDRIVER type list disk , Identify the correct disk by the size and then replace the Disk 0 below with the appropriate number
5.type select disk 0 then select partition 2 then assign
6.open windows explorer windows+e
7.refresh if the drive is not showing F5
8.try to open drive by double clicking
Try elevation, create a shortcut on the desktop to cmd (Just type cmd) and save, then right click the shortcut and select run as administrator. Then try the commands listed in the article.
diskpart
list partition
select partition x:
assign letter=b
exit
(Where x: is the number of the partition listed by the list partition command and b is the driveletter you wish to assign to the EFI partition)
Now kill the File Explorer process and start it with administrative privileges:
taskkill /im explorer.exe /f
explorer.exe