However, as David “Xrm.Tools” Yack reports, sometimes pending keys are really stubborn and pressing Create Index generates very introspective and philosophical “Exception: Event failed due to an exception” message. Reactivating the key does not work either because it’s only supported for failed jobs and getting an exception apparently is not really a failure.
Another toolman, Tanguy “The XRM Toolbox” Touzard, to the rescue!
This stalemate can be resolved by deleting the failed job. That seems to allow you to re-activate it and re-create the index.