Can happen iron core to became magnetic and to annulate the effect of moving magnet.
That is why the screwdriver demagnetizer tool exists.
From picture when coil is out of the holder inductance and resistance seems OK.
But fot that many turns I expect larger induced EMS. Either core is magnetizied or magnets on moving part is weak.
The moving magnets are the same for both the old and new sensors so don't explain the difference.
The core becoming magnetized is an interesting theory - I'm not sure how I can test it though as I don't want to remove the new sensor.
I guess if this is the problem then it could be demagnetized with an AC signal ?
If I get the chance at the weekend, I might experiment with the old sensor, my scope and a magnet held in my hand to act as the signal and try different cores.
Note, the moving magnets are not that close to the core when they pass - it is several mm (it is a bit hard to measure as it is behind the flywheel) so the magnetic field is not that strong.