I installed MacOS Sierra Beta 1 and I had to fall back to OS X 10.11.6. MacOS was unable to recognize my USB drive. Now that Beta 2 is out and I am the optimist - I would like to move forward and try Beta 2. But when I go to the store the the Purchases tab indicate that OS X Beta 1 has been downloaded - but greyed out. If I attempt to go to the Apple Beta site and re-register my Mac it says that the code has been redeemed. Any way to get past this?