There is a bug on duels.

[the real god emperor]

Hello, i was dueling on EU3 few days - maybe a week - ago then i saw there was a bug at sending duel invitations, when you first came to server, you can properly send them . After few duels, it starts not to send duel invitations, so you cant duel, you can begin dueling again if only someone comes in the server recently, and sends you an invitation. Please work on this.

Regards,
Kratos

[MrShine]

I'm shocked this has no other responses - NA 3 has been like this for months now.  You can get around it by re-joining the server or by having someone without the bug challenge you to a duel... but it's just obnoxious.