I've seen a workaround for this problem on the internet, but can't find it again. The problem has something to do with the current pdf not having embedded fonts-- whatever that means. It's an inherent flaw in the Acrobat software that Adobe needs to fix. But the workaround involved closing the document and then opening it again in a particular fashion.
But now that I've pointed us in the right direction, maybe someone more knowledgeable can provide a solution.
North America
Europe, Middle East and Africa
Asia Pacific