In need of experienced opinion

I purchased a *NEW* Nikkor 50mm f/1.2 ai-s. It's for use on my Nikon FE.
at 2.0 i get accurate exposure from the meter.
at 1.4 i get accurate exposure from the meter.
at 1.2 - the meter exposes exactly the same as 1.4 !

Note: the blades fully open at 1.2, so more light is definitely hitting the mirror.

I'm guessing the FE's meter cannot read at 1.2 lens...

is anyone aware of this? or have you experienced otherwise?

(A Nikon service adviser said they would investigate and touch back, but thought at 1.2 the lens may "uncouple". - Im not familiar with that terminology - i'm awaiting their reply on what they meant by that. For sure they didn't mean the lens would fall off camera )

thanks
m

F/2 is a stop difference from f/1.4

F/1.4 is only half a stop difference from 1.2

a quick google kinda makes me think the camera is metering in full stops. If that is the case, it is not that unusual that you may not add enough light to move the meter another full stop.

Uncouple may be a reference to the aperture mechanism on the lens moving away from the lever it usually drives on the body to inform the body how far closed the aperture is on the lens.