Here's an update: I installed Thunderbird and entered the values shown on the CNS help site that I posted in my initial message. I also tried deleting and re-entering my account in Mac Mail. In both cases, I got the same symptoms: everything syncs except my inbox (that is, I see calendar events, trashed messages, and sent messages, but no messages in my inbox at all).
Any advice on how to troubleshoot from here? Perhaps there is a glitch in my inbox settings from the server side? I can bring the computer in to CNS on Monday, if that would be the best approach.