Einstein Copilot isn't making any plans

I've activated the Copilot in an SDO, to test it. So far, I've managed to activate the Copilot, and even create a custom action and prompt.

But, no matter what I write, the answer is always the same: "Something went wrong. Try again."

Even in the Copilot Builder. 

In the central area of the builder, where the plans should be shown, nothing happens.

What am I doing wrong?

PS: permission sets are ok.