I can't duplicate this bug when I try, but I've been seeing it for years. Do you understand the conditions that trigger it? Is there a workaround? Notes are sync'ed to an IMAP account on my server, not iCloud.
I know there are a ton of way-more-complex note-sharing apps out there with way more features, but I really only need something dead simple -- I need nothing more than what Notes does, minus this irritating bug -- so evangelizing all the hairy features of other apps will be uncompelling.