Non-zero stress and strain values for zero displacement with no preloading

Hi, I am trying to validate a compression test of hyperelastic material silicone. So I have taken a single cubical element of 1mm dimension and I have applied a prescribed displacement upto 0.5mm in compression. Now I am facing the following difficulties:

1. The cube is bowing inwards rather than bulging outwards for the compressive loading. (Image attached) The response does not improve by meshing with multiple elements.
2. There is non-zero stress (too high) and strin values for zero displacement of the element. (I am using auxiliary sweep) (See the probe table in the image)

I am using Ogden Model with N=2 for compressive test data.

I have been facing these high strain and stress values even for 2D simple models containg hyperelastic materials. One peculiarity is that the stretch value was correct but the strain was too high violating their relationship.

Can anyone please help me out with this?

Thanks.

compression.png