Data source table view problems

I’m working with a data source connected to a table view. I can successfully add & modify things in the data source and have them show up in the table view, but I’m having some problems with the sorted and sort column properties. After settings these properties and telling the table to update, the first and last items in the table swap. Nothing else changes.

This behavior seems pretty strange, and I can’t figure out the why it’s happening. Has anyone run into this problem before?