I made a quick search on hall sensor, in effect depending on how your ignition brand designer conceived the system; they will use different types of sensors.
The magnet position definitely makes a difference.

The hall sensor may be divided in three different categories:

Bipolar Hall Effect sw sensor
Unipolar Hall Effect sw sensor
Omni polar Hall Effect sensor

[link=http://www.allegromicro.com/en/Products/Design/an/an27705.pdf]Hall Sensor categories[/link]

Otherwise depending on whether or not BME used the same system as 3W or DA, the observations about hall sensor and magnets may change.
I think they are still useful.

As far as having a broken or cracked magnet I can’t tell for sure. I may need to extract the magnet to know, however the sole fact of extracting the magnet may breake it anyway.

The halls sensor is an electronic device, it could very well triggering by the effect of a hysterisis effect or so. Noise can trigger these circuits as well.