Hi SkyBlue75,
Thanks for letting us know. Trying steps can possibly help resolve issues or isolate what might be going on. To confirm, are you able to use AirPlay with other apps while your iPad is in portrait mode?
Also, please let us know if you were able to try restarting your iPad. It can seem like a simple step, but it can sometimes help resolve unexpected issues as it can refresh the software and apps. If needed, the steps below show how:
"How to restart an iPad without a Home button
- Press and hold either volume button and the top button until the power off slider appears.
- Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
- To turn your device back on, press and hold the top button until you see the Apple logo."
This information is from Restart your iPad - Apple Support.
Take care.