I was helping a friend who was going crazy trying to add a JetPack custom form to a page.
He was seeing the shortcodes in his post after entering the form, but they would disappear as soon as he clicked Update.
Finally I said, "Let's try a different browser." He switched to Chrome and it worked fine.
So the problem appears to be with Internet Explorer 9 (latest version).
Any solution to doing this with IE9?