forces of restart

Dear all,

I am trying to simulate the breakage of a granulate, which is formed by small particles, by pressing it using a servo-wall.
I observated the forces on the wall, it worked very well. I wrote also the restart files every xxx time steps.
However, if I load the restart file (and the current stl of geometry, because the wall moved) and want to simulate it further, the forces on the wall are totally gone, after many steps they can not reach the value I had earlier.

Is it because the accuracy of the written restart and stl files?

Has someone the similar problem? How could I solve it?

Thanks a lot!

best regards

Zhen