You have created exception pages in a language that contains special characters (e.g. japanese). However, users only see a list of question marks instead of the actual characters.
This can happen if the page was created via the command line. Some terminal utilities do not properly translate these special characters. In that case, when you look at the text configuration, you will already see the question marks there.
The solution is to use the ProxySG Management GUI (Configuration -> Policy -> Exceptions -> Install Exceptions Definition from 'Text Editor' -> Install).