When writing notes on a Mac device (theoretically iPads and iPhones too but we won’t know until notes are enabled there), the line breaks don’t register at all (possibly because they’re CR instead of LF/CRLF), not even when trying to use two or more to break a paragraph. They don’t even count as spaces, so words I want to be in separate paragraphs end up concatenated…
We have ambitious plans for note-taking which will start taking shape once we’ve released some of what’s currently being worked on and will include rich(er) formatting options. A workaround in the meantime could be using dots (periods), dashes or other symbols to separate paragraphs.