Hey Dustin! If you used our Duo Unix protection using PAM, you might need to provide the absolute path for the pam_duo.so shared object inside the PAM stack you configured. Above the examples in the documentation we mention that the location of the pam_duo.so might be in /lib64/security/ on some OSes or achitectures.
If your line looks like this:
auth [success=1 default=ignore] pam_duo.so
Try editing it to this:
auth [success=1 default=ignore] /lib64/security/pam_duo.so