Brian, the M22 has been designed with an enclosure tuned to about 59Hz(shown by the low point in the bass impedance valley)and the Axiom spec shows good response down to at least 60Hz. My personal use over about 25,000 hours has always confirmed this and the Audyssey measurements for calibration resulted in a 60Hz setting(which I raised to 80Hz to give the EP500 more work), indicating a measured -3dB point somewhere below 60hz.
I just now repeated a test I did long ago with my Stryke test tone disc. It includes a 1Hz to 100Hz continuous sweep band which takes 5 minutes to complete. Setting my M22s to full band and no sub, the sweep began to be audible a bit under 40Hz, and the 60Hz-100Hz frequencies were continuously strong and certainly had no "hole". Whatever you're experiencing isn't typical to say the least. Both the measured and audible results confirm the competence of the Axiom design and the accuracy of their specs.
