Ok, I just noticed a new issue because I still can't get the update to work. I was going to trash my FCPX app and redownload from from the App Store as others have suggested. Well, when I go to the App Store, it still gives me the option to buy FCPX, even though I paid for mine and I still see the charge on my credit card...
what the heck...
Edit:
Ok...If I go under purchases in App Store, I see FCPX there but it give me the option to install, like I've never downloaded it before....Trying that now.
Edit 2:
That did the trick for me.