In 0.2.3, the Oculus Unity integration is doing the mag calibration thing differently. Prior to 0.2.3, that checkbox simply toggled whether or not the OVRMagCalibration.cs' UpdateMagYawDriftCorrection() method would do automatic or manual calibration.
Now in 0.2.3, which type of calibration done is decided by the user when starting calibration. You'll see this in UpdateMagYawDriftCorrection() in 0.2.3: