Collision between object is abnormal

[gabrigoo]

Hello,

I am fairly new with pybullet and I am having some issue with my simulation. Basically there is a cube on a table and as soon as a robot tries to touch it the cube acts abnormally and "enters" the table. I will attach a small movie so you can see.

I am using pybullet in python, let me know if you would want me to share the .obj , .urdf files.

Thanks!