Frequencies analyze not outputting right values

Hi everyone,
I’ve been working on a frequency analyzer for few days now. I am using the TimeSynthComponent and make it play a TimeSynthClip.
For now I just want to play a .wav file that correspond to a A 440Hz wave.
When I play the clip, I also enable the spectral analysis on the TimeSynthComponent, and add frequencies in range of 200-600Hz (I don’t need more for now) in the array of frequencies to analyze.
Then on an input, I call the GetSpectralData function, print their values (I both plot it in an UMG and tried also in Excel), and as result I got the highest magnitude at 469Hz instead of 440Hz (in audacity for the same .wav file I have the highest magnitude at 441Hz in the spectrum).
If I try with a C 260Hz I have the highest magnitude at 282Hz. And with a A 880Hz the highest magnitude is at 844Hz.

Here is the TimeSynthClip:

Everything else is at its default value.

And if I plot the values at each frame, the curve is continuously changing, actually it should be everytime the same no ?

Do someone have an idea on how to solve this issue ? Does it come from my setup ? Am I missing something ?