Congratulations on completely destroying the sync ability of the iOS version of OneNote. Your mother must be so proud.
Update: Surprisingly, it still worked on my iPhone while being totally borked on my iPad. None of the fixes people have been suggesting in the forums (lots of people hitting this bug this week) fixed it. Failing to authenticate for sync has actually been an issue with the iPad version of OneNote for quite a while, but in the past, force-quitting the app was sufficient to fix it. It looks like a nuke-and-pave of the app is necessary but not sufficient; I’m not actually sure what eventually persuaded it to start working again, but I suspect it was the animal sacrifice.
An app whose functionality depends on reliable sync needs to sync reliably. I migrated everything over from Evernote and let my paid subscription lapse because they were ignoring the core functionality of “sync my notes between phone/laptops/tablets”. Your recent attempt to provide the (not-quite-the-) same (poor) user experience on all platforms is the sort of development diversion that cost them customers.
Oh, and if you really want to make the user experience the same, add the “Recent Notes” tab to the desktop clients. It’s one of the most useful features of the mobile clients, and completely missing on the full app. And bring the Mac client up to feature parity with Windows, maybe?
Update: Happened again on 6/6. I had to delete the app, re-download it, and then re-sync all my notebooks. WTF, MS?
Markdown formatting and simple HTML accepted.
Sometimes you have to double-click to enter text in the form (interaction between Isso and Bootstrap?). Tab is more reliable.