My microsoft authenticator wont let me accesz my whatsapp app?

I bought the Microsoft authenticator app to lock my WhatsApp app. It has worked for over a year and now when I put in my four digit code, it opens WhatsApp for one second and then bounces right back to the page where once my four digit code. It will do that consistently and never let me in. I have uninstalled, reinstalled, changed, passwords everything I could think of, and I still cannot access my WhatsApp app