Texture marked with 'cube' shape cannot be assigned to the material

[Betweenwinters]

I previously marked my sky texture 'cube' with cylindrical mapping, however, it cannot be assigned to the unity sky-mesh material.

I changed the texture to the normal 2D shape, it was successfully assigned, however, all of my game geometry's texture is washed away with the sky texture, except for the transparent texture.

Could you please give some insight on this? Thanks in advance!