Thanks for your help Vero. Problem is fixed. I ran Troubleshooting and it pointed to a Mac indexing issue. Then I remembered that a while ago I had told Spotlight not to search the volume where my apps are located because of a Spotlight problem I was having at the time but is now resolved. I added the volume to Spotlight and that did the trick. I actually wasn't sure if Alfred relied on Spotlight but now I know it does.