Abaqus - Help with weight load on buttocks diverging simulation

Hi all, I'm new to Abaqus and trying to model a 1.4 kg weight laid on the buttocks.
I have an imported buttocks model with element type C3D4H for the hyper elastic materials and C34D for bones.
I assigned boundary conditions of encastre to the bottom part of the buttocks, U3=0 to the side of the buttocks and the weight can only move in direction toward the buttocks.
I'm using prescribed displacement of the weight and measuring the RF2 on the top nodes of the weight and trying to get ~13.7N (1.4*9.81).
I've assigned surface to surface contact with 0.8 COF between the weight and the area of the buttocks in contact.

I cant seem to get convergence at other part rather then the middle of the buttocks, when the weight is above the peak height...
I tried many things but cant get it to converge, It start to get really slow around 80% and diverge at around 95%, when the loads get to ~12N. Also the deformation seems a bit large for this small weight.

I would really appreciate some help, I'm attaching link to the cae file with 3 locations of the weight I tried.

https://files.engineering.com/getfile.aspx?folder=24af7b7d-5042-4c30-a3e2-c446c87cd7e9&file=ButtocksModel-Front-Mid-Angled.cae


Thank you,
Tomer






Abaqus ​​​​​​​