Guide for sshd may need to add in confirming challenge response authentication is enabled in /etc/ssh/sshd_config (per the CentOS related blog referenced in the page -  )
# Change to no to disable s/key passwords #ChallengeResponseAuthentication no ChallengeResponseAuthentication yes
systemctl reload sshd
Before I added this in I was getting Permission denied errors
$ssh firstname.lastname@example.org email@example.com's password: Permission denied, please try again.
I was setting this up my Pi3, but it doesn't look enabled by default on my x86_64 laptop sshd_config.