Troubleshooting Tips
Restart your device - if a device will not shut down, in most cases holding down the power button will force a restart
Do a hard reset on an iPad with a home button
If you have an iPad without a Home button you need to:
Press and quickly release the Volume Up button.
Press and quickly release the Volume Down button.
Then press and hold the Power button until the device restarts.
Update your device - make sure it has the latest operating system (Catalina or Big Sur for MacBook, iOS 14 for iPad)
Restart the app
Projector problems - check cable connections on both ends, unplug and replug any dongles
Google for answers