Board Game Arena

How does diplomat works?
I took 2 attacks from the Picts in the right side. One of them was defended by the cohort, and the other one was supposed to be defended by the diplomat, but the system didn't offer the option to use the diplomat for defense. In the end, I received a disdain without being able to avoid it.

I don't think they're working properly at the moment. I've had times when they allow you to cancel a pict card, but most of the time I'm not allowed to cross out the circles. Someone can correct me if I'm wrong.