Simlation with physics does not behave as expected

Hi,

We are having some difficulties in a relative complex simulation, regarding physics. To experiment things out, I have made a simpler project.
As can be seen in the video below, whenever the robot moves down, the box temporarily gets inside the support, until it stops. If I increase the damping, it can even pass through the support and fall in the floor.
I am also leaving a link to the project itself, if you want to check it out.

I have experimented with changing the material parameters, decreasing the simulation options (timestep, physics timestep) and increasing the collision geometry detail, but the result is the same.

Any help will be appreciated.
Video Link
Project Link

Thanks and best regards,
Hugo Costelha