thank you for your example. It looks really interesting and difference in solving time is remarkable.
I will check my solution with linear solver once again.
Best wishes, Michael
Simple answer: the iterative solver is numericaly less stable than the direct one but results can be trust regarding what you said.
Indeed, you have generated contact element with gaps and the contact algorithm needs to find balance at the begining which is almost impossible : the pins may have a tinny rigid body motion before they become in contact and balance is find.
This is why you will always have such message when gap are not closed at the beginning of the analysis.
More than a numerical problem, this is a physical one.
Try to overiden your gap at 0 and the iterative solver will behave.