i think its in the design, meaning the multiple, wider horizontal lines in your stencil are causing the squeegee to 'stutter or hiccup' after the squeegie makes a pass on the open areas..
Open areas are in parallel with the squeegee, causing the blade to 'jump', leading to the pre mature screen break down immediately after the open areas.
At least thats my 2 cents. We have seen it happen here. Back off pressure, softer squeegee or more angle is a fix.
John