-- Make a backup to PC or email the notes to yourself as an attachment
-- Turn off and delete iCloud from both devices
-- Turn on iCloud on the iPhone and make sure Notes is also turned on
-- Turn on iCloud on the iPad and make sure Notes is also turned on
If that does not work then I am clueless and maybe a call to Apple would be in order.. You may have data stuck or corrupted on their end that's causing the issue and they may be able to thoroughly delete the iCloud data..