Forcing Windows 8.1 update through the Store app
Some people have had issues getting the Windows 8.1 update to show in the Store. There is an easy way to force the Store to update.
Goto Run (WIN+R) type in: "ms-windows-store:WindowsUpgrade" (no quotes)
You can then verify progress by then running (Win+R) "ms-windows-store:InstallProgress" (no quotes)