Landscape on Mobile is broken

UDN: https://udn.unrealengine.com/questions/431532/landscape%E5%9C%A8%E6%89%8B%E6%9C%BA%E5%B9%B3%E5%8F%B0%E6%98%BE%E7%A4%BA%E9%94%99%E8%AF%AF.html

1. New a default level and create a Landscape
2. Sculpt the Landscape a bit, built lighting, save map
3. Don't use any mobile Preview in Editor or the problem will not be reproducceble
4. Run the map on Mobile(both IOS or Android)
5. The Landscape is broken at the seam of each component; it looks like the same height information is repeated on every component
6. Not only on Mobile, but now use Mobile Preview on PC, the Landscape is also broken

If use Mobile preview(Default High-End Mobile for example) before cooking and delivering it on mobile, no problem!

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