Why is there no land in Sansha City, Hainan?

I also wonder why Sansha City has been set up, but there is still no Sansha City in Hainan's weather forecast. It's strange to use "Yongxing Island in Xisha", Huangyan Island in Zhongsha and Yongshu Reef in Nansha to forecast ... but it's on the map. The island blocked in the South China Sea on the small map in the lower right corner or the lower left corner of the map is Sansha City.