First of all, forgive me if I have a word mistake I write this using Translation.Firstly, when I enter the game and drop the Chunk, it is loaded halfway beyond 15 meters but my front is not loaded.

currently, terrain generation is slow (see here for more information). if you move around before the terrain can load in completely, it'll end up looking like what your screenshot.

you should quit the world and open it again, then just wait for all the terrain to load in (which can take a long time). alternatively, use CubicWorldGen, which is significantly faster at the moment.