Figured I would post about this here as it seeems like I've tried just about everything to get this thing to stop coming loose. I emailed the Winow rep Terry and received instructions for cutting the steerer that I haven't seen anywhere else on the internet. it seems you are supposed to have it so the expansion plug is almost flush with the top of the stem then you add a spacer above the stem + the top top cap in order to increase the clamping area of the already lackluster stem on the steerer.

I think I only have it about a mm or two shorter than in their photo which I don't think would prevent sufficient clamping yet just pushing down on the bars and bouncing the front wheel off the ground seems to very quickly loosen the whole headset and the fork will move back and forth. I also tried adding carbon grip to the expansion plug and isopropyl alcoholing the grease off of the steerer tube.

Pretty close to just ordering a new fork and a different better stem so any input is appreciated and will likely help others that want to buy this frame in the future.