We have many courses in our Moodle and are currently running the weekly build Moodle 2.3.4+ (Build: 20130131)
Brief: If you have a couple of assignments or resources setup in the course, you can move the items down with the handlebars or with ajax off, the manual mechanism. But, if you attempt to move the elements up, nothing happens.
Create a course
Add a resource or assignment to the course
Move either the forum resource or newly added assignment down to a different section
Refresh page to verify ajax worked
Move that same resource back up to a different section
Refresh page to verify ajax worked (which it fails to write).
I analyzed the sql and the UPDATE mdl_course the sectioncache field does not get updated when moving elements up. It comes back with the exact same information that was already in the sectioncache field. I am still troubleshooting the issue and will post any additional details I find related to this issue.