I'm using 2FA on Ubuntu 18.04.4 LTS with Google Authenticator. I added auth required pam_google_authenticator.so nullok to /etc/pam.d/common-session and correctly set up Google Authenticator.
The 2FA works great when getting back to a session after sleep mode. However when I shut my computer down and boot again, the 2FA doesn't prompt and I'm only asked to enter my master password. Do you have any idea why?