This is not a new problem - just thought I’d bring it up again now that summer is over and you might have some time to look into it.
If you use a Number Sign (#) or an Ampersand (&) in a post the Preview will only show the text up to the offending character. If you remove the character the post will preview properly.
I usually work around it by using No. or And so it’s little more than an annoyance, but it would be nice if Preview worked with (and for) all characters.