I am running a nonlinear analysis for latch/snap. The model and motion are pretty simple. 

The analysis is not failed during the bending, but failed at where it's almost done. And the stress distribution is not even. As the screenshot below, it's concentrated at one side.

Sometimes it will pop out "Improper Contact Surfaces for a Contact Area", sometimes it just says it's failed.

I didn't find much info about this error message, so just wonder what's the reason for it?

Is it possible because of improper contact set setting, mesh size, or is it because of the steep edge of the latch? 

If I add a 45 or larger degree tilt to the rear end it will succeed. But why vertical wall does not work?

I attached the model(SW2019) for reference. Thanks for any idea!