Same problem here. My HMD (with LED ping pong ball) tracks in psmoveservice but does not track in steamvr.
I have the freepie installed and I run the example script.
I notice that driver4vr exposes two buttons when “freetrack” is selected for head tracking. Clicking the configuration button opens a window showing freetrack data. My position and Raw angle data shows zero even when the HMD led is moved. The Available field has the value “True”
I have tried checking the box for “read raw data for position” but it does not seem to affect anything.