Same issue with the Yubikey not working with this plugin. I tested the key on other sites secured with Yubikey. They work just fine.
Also tested a brand new backup Yubikey on my wordpress site. The Yubikey doesn’t seem to be the issue. The issue is the plugin.
I had to go into cPanel and rename the plugin to access the WP dashboard. When I logged into the dashboard, I set up email verification.
That works okay, but a short random numeric code sent by email is a lot less secure than Yubikey’s long random alphanumeric codes.
Is this something the developer is aware of and intends to fix soon?
The same issue with YUbiKey on my site.
@o3digital
Problem is solved. Thanks so much for this fix!