Akritoi Defense not working

Hello everyone!

I enjoyed multiplayer yesterday as Byzantine against Japan. I used Akritoi Defense twice during the match, and it worked only once.

I have confirmed through the replay that I indeed used the ability, vils were within the radius, and the vils used puny Knives instead of spears while being slashed by Samurais (they repelled Shinobis with spears earlier in the game).

Has anyone experience this kind of behavior?

Thank you!