DvZ

I had the same problem for weeks and I finally found the problem. In my case it helped to reset the Search Scope in the Default Results screen of the Preferences and then restarting Alfred. In case this doesn't help, try quitting Alfred and move the file ~/Library/Application Support/Alfred 3/Alfred.alfredpreferences out of the way. After this, if Alfred doesn't give the "Waiting for results" message anymore, you know for sure something in your preferences has gone haywire. If you're feeling adventurous, the Alfred.alfredpreferences file is a really a directory ("bundle" in macOS terminology). Try to rename one directory at a time (make sure Alfred isn't running when doing this). This way I found that my Default Results were faulty.