I am continuously encountering a '1001 No Fill' error while testing ads on iOS. The demo app provided by the Facebook team (https://github.com/fbsamples/audience-network/tree/main) also results in this error. Refer to the attached image for more details. This error occurs on both the simulator and the test device.

The Placement ID, obtained from Facebook Business Manager, is 268388542921605_268389539588172. For testing on a real device, I have added its IDFA to the platform.

It was tested on different iOS versions, including 16 and 17.