Hello jhg1,
Thank you for using Apple Support Communities!
Based on what you mentioned, you are having trouble with how scanning works in Notes on iOS. Is the keyboard showing on the screen when this issue occurs? If so, tap "Done" in the upper right corner and see if the Camera icon shows at the bottom of screen. Tap on that to use the scan feature.
If that doesn't help, force close the app and restart your iPhone using the steps here:
How to force an app to close on your iPhone, iPad, or iPod touch
Restart your iPhone
Then try once more. You can read more about scanning using Notes here:
How to scan documents on your iPhone, iPad, or iPod touch
Best wishes!