@Xiaotaotao—
Every now and then someone uploads a long-strip to MangaDex in the form of one image file that is tens of thousands of pixels in height. Users on slower connections get hit with a time-out, and some browsers even on fast connections won't render these images, but the works-for-me crowd just thinks that everything is fine.
On a fast connection, Opera on Android will render this image. Kiwi will not, but the image can be saved from Kiwi and viewed with another application. It's probably likewise with other operating systems and browsers. If you are on a slower connection but can get the image URI, then using CLI command wget with option “-c” is your best bet. Otherwise, you're probably just screwed until-and-unless another scanlation group creates a proper upload, or this group acknowledges its error.