I tried reboot still notes iPad not sync match iPhone. I try turn iCloud notes off then on still nothing.
I can't believe if you need set up folder for every device!!
Edit: long way round fix problem. Copy note and paste new note in right folder iPhone and it appear right folder iPad fine. I did that all notes and now finally work. Hard work lot lot lot lot notes!!
I'm inclined to go with Paco II's explanation. I was having issues with Reminder/Calendar items not syncing for almost a day, then suddenly started working just fine again.
This has definitely not been a smooth upgrade for me. Notes syncing issues, third party app syncing issues, iCloud backup only sporadically working. Seems like most of my main issues track back to iCloud.