Out of spec - Yankee Hill Machine AR Rifles 300 out Dust Cover w/ Dust Cover, Rod, and Retaining Clip Spring

This is my second .300blk build. It doesn't keep the dust cover closed. It's almost like the spring tension in built into the dust cover isn't strong enough to hold it in place. I replaced it with a blank dust cover, and that works fine. So don't understand what went wrong with this product. Will try again with a different brand