Since Audition CC is quite a considerable advance on CS 5.5 there are quite a few changes to the way session files are written which makes them not fully backward compatible with earlier versions of Audition I suspect.
The bulk of the session should be backwards compatible, but some effects from newer releases will not load in earlier versions, as you've noted. For compatible effects, you should see the correct parameter values, though the preset name used will not be displayed. (Presets are a trigger to adjust parameter values, not stored as a parameter itself.)
Thanks to both of you for your helpful advice. I'll have him resend the
session with the other five effects in the preset, and the values of the
one that used the Single Band Compressor. Great solution. Thanks SO much.