I was involved with the testing of the TP20 Probe prior to its release and conducted several tests with mag bases. The occurrences of the probe inhibiting when in proximity to a mag base were very rare. I had to turn the mag base on its side for this to happen. The magnetic field has to line up with the reed relay in the probe body for the probe to become inhibited. I will not say that it is impossible for this to happen, but have only seen 1 or 2 cases of this nature to date. When probing around magnetic bases and/or parts with any probe, care should always be taken choosing the right stylus length to avoid the magnetic field as much as possible. Same can also be said when choosing the stylus material.