IOS – Will Siri work with 3rd party apps after update from iOS 9 to 10

Thanks for the suggestions but here is the answer:

The reason this happens is because every time a downloaded app is opened it checks for your itunes password for validation that you are authorized to open that app (as it may contain personal info). From time to time the iphone “forgets” your itunes password. You can fix the missing password by syncing the iphone with itunes or downloading an app from the app store and entering your password that way.

I am up and running with all my 3rd party apps now.

I use Notational Velocity and Simplenote apps on iPhone and iPad and the Simplenote web site as well and while I see you want to stick with Apple's notes.app I think you'll find Simplenote excellent, maybe better. I've been using it as long as it's been out and it's stable, simple, and has always worked for me.

If Apple mated the Notes app with something on the Mac I might never have tried Simplenote but it's cumbersome as you say to have to use Mail to deal with notes. Notational Velocity's integration with Simplenote is probably what you're looking for.

Simplenote is free, give it a go.