This is an interesting one that’s just come up while we were testing the new version of Search Replace DB. I’m calling it the Cheshire Cat Bug because when I found it I was using a smiling cat.
Basically on my various MySQL installs if I use a three byte Unicode value for an icon like ? it and the content after it gets disappeared. In fact, even switching to the visual editor just mullered this post.
It’s not WordPress that has the problem, but MySQL. I’ll research the problem thoroughly with some tests and some Googling when I get a bit of time, but if you have any ideas, do let me know!