Firefox 11 bug
Firefox 12 fixes this issue. Please update your Firefox if it hasn’t already.
For users using Firefox 11 (newest version,) there is a bug on the edit screen where the first editor on a page with multiple editors shows no content. Do not worry, that content is still in the system, but there’s a bug with displaying it.
If this bug is affecting you, please use another web browser for the time being. Because of the widespread nature of this bug, it’s possible that Mozilla will patch Firefox to fix this bug. We’ll send out an update when this issue is resolved.
For more information on this bug, please see: