EVM inductance reading not correct

I have a 230uH coil with a 220pF capacitor and it oscillates happily at exectly 700kHz.

I checked this with te skope and a pickup coil as to  putting as minimal load as possible on the system.

Now the EVM reads out 210uH which is about correct. with the amplitude set to 4V.

When I change to 1V or 2V the EVM starts diplaying 175uH. 

Now the displaying of the measured inductance is actually derived from the measured frequency and the capacitance value in the drop down box,

So its actually the measured frequency there what I see -> correct me if i'm wrong.

My skope keeps confirming the 700kHz in all cases, but the inductance reading is not constant ,and so must be the frequency measuring.

I supposed it has to do with the CFB cap and the voltage on the CFB pin. with 1V and 2V setting the signal is 1.4Vpp,

but with the 4V setting the CFB signal stays below 900mV

So I changed the CFB cap to 47pF but the behaviour is about the same -> no correct reading of inductance  at 1V and 2V

Can this behaviour be explained please ?

I suppose that when the frequency measurement is not correct , things are not running well inside the chip , and that other readings cannot be trusted as well ?

I ask this question because there are certain settings of the registers where i get a really good response from the target material ,but the frequency is wrong.