Airplay mirroring with peacock and hbo max

When I use the HBO MAX app, Airplay Mirroring works fine. But using the Peacock app is problematic. With Peacock I get mirroring as I’m browsing but when I start a show, the audio is mirrored but the video is not mirrored, it only shows on my iPad. I mirror to a 3rd gen Apple TV. If I get out of the Peacock app and go back to the HBO MAX app, mirroring works fine again, audio and video. It also works fine for the Prime app. So I know I have a good connection and my devices are compatible. Is this a problem with the new Peacock app? Or am I missing something? Thanks.