I'm using this plugin for 5 months now without any problems. After the last upgrade to 1.13 I'm facing a strange behavior. When I'm on draft mode (previewing the post) it shows the Crayon box with a single empty line 1. The same post was previously published and was working perfectly. Now When I'm trying editing it and previewing changes the problem appear. Any new post doesn't show the code all I got is the empty box!!
Here is a post that has Crayon works:
The same post without any modification but in preview mode has Crayon not working.
By the way I tried changing the theme and changed it to Twenty Eleven (default theme chipped with WordPress) and the problem remained.