After riding the Giant for a week the rear axle continues to slide forward despite the dealer adding a washer to the rear axle.
Have adjusted the chain side of the axle of the rear wheel to regain tension. Now the wheel is off center, meaning that both sides of the rear axle are sliding forward, causing the chain to drop off and preventing the brake from working.
Currently dealing with Giant to see what can be done to fix this design flaw. I may have to add several bolts into the axle mounting slot and see if that stops the axle from sliding. This is a serious design flaw that could lead to injury.