I have the same exact issue.
I bought Alfred last week and the snippets stopped working all of a sudden today. (Catalina 10.15.5)
On the app it says that "Login window is preventing text expansion by locking secure entry"
I have all apps closed (even my browser).
Any ideas? I bought Alfred mainly for this function as a better alternative for TypeIt4Me (which I've completely uninstalled) as I rely on this function on my every day work.