We had this same issue, I read this forum and spent most of my time working out what FWC meant.
I have always called it the csf profile, but anyhow it is the same problem and is indeed fixed by changing the settings in the csf profile for Jabber unde...
I had this problem and I fixed it by assigning the user to the DN, however the main caveat is that I had multiple UDPs and I needed to make sure every one of them had the DN associated with them. Even if you are using one that looks setup correctly....