@ naivedark
I get a different result.
If the Windows 8 (Metro) Menu shortcut is unpinned from the "Start menu (Start8)", to get it back I just RMB clicked on the Desktop and created a New Shortcut pasting in the following for the location of the item
"C:\Program Files (x86)\Stardock\Start8\Start8.exe" Metro
and then clicked Next and I gave it the following name
Windows 8 (Metro) Menu
then clicked on the Finish button. (And I moved the newly created shortcut from the Desktop to another folder location.) I then RMB clicked on the newly created Windows 8 (Metro) Menu shortcut and clicked on "Pin to Start menu (Start8)"; and if wanting to change the icon just RMB click on the shortcut, click on Change Icon, select the icon you want and click on OK.
However when I did this all worked as expected (i.e. as it did before my unpinning it). I wonder why it behaves differently on yours. . . .
regards,
Laurence