I have mocked up a simulated assembly, 95% of the time the results are fine the peak stresses show up on the front portion as expected. Then I get results that show them on the back side of the part (side with the pressure on it). I have tired rebuilding the assembly and sometimes this helps but other times it doesn't. Also the result isn't what is expected either, typically too low. I have altered the mesh and tried to change the thickness to see if it is an indication of too thin or too thick of a part.