Thanks Roger.
The 3.3.0.11 was running on a testing server and the admin told me it could be a problem with AJAX trying to contact the production server to get the checklist. We downgraded back to 3.1.1.4 and manually defined a checklist and upgraded back to 3.3.0.11 and now it loaded the checklist without problems. It probably is a bug when the checklist has not been previously defined.
Thanks for the help.