Even after doing the following: "You can force macOS to reindex that folder by dragging /opt/anaconda3 (or even opt) into the Privacy list in System Preferences > Spotlight, and then removing it again." - neither Spotlight nor Alfred can find Anaconda Navigator.
There is something peculiar about Anaconda-Navigator in another sense on the Mac. When I run it and then exit the app, it does not remain on my Dock as one of the three most recently invoked apps, the way all other apps do. This may be a separate issue (that has nothing to do with Spotlight or with Alfred) or it may provide a clue.