Herald lvl 19 can't revive anyone

I am in a dragon battle with the Highland Ravager. My main character a Qunari mage level 19 has lost his ability to revive anyone.

My standard team always includes Dorian, so he's always there, he also has the revive ability. When any character dies in this battle I try to use revive. But there is only a green light flash

but the resurrection animation with the angel wings doesn't happen, the revivification just stops there and fizzles out. Dorian, however, has his ability fully intact.

So, if someone dies I have to wait for Dorian's automatic revivification, if Dorian dies then I've lost him for the entire battle (even though I have revive)

If I die, then there is a possibility that Dorian can revive me.