Can’t use AS miles to book AA flight.

Minor harrumph.

Plat pro flyer. What good is having a partner airline if we can’t use our partner/AS miles to book an AA flight? Plenty of seats and tried variations to my destination, and yet….

“We're sorry, we aren't able to confirm space on these partner flights. Please try again and choose different flights, dates or cities.”

Any suggestion? Other posts say say I’m just out of luck in this situation.