Donald Wilson joined the community
mail.app no longer appears in Alfred's hotkey search list. mail.app does appear in the spotlight search. I rebuilt the macOS cache, initiated from the Alfred preferences screen. Didn't fix the problem. I'm using Alfred 4.0.2 now, but the problem was discovered when I was using 4.0.1. I upgraded to 4.0.2 in order to see if the problem would go away or was fixed. I'm using MacOs 10.15.