Wp admin：无法上传和查看精选图片

WordPress helps to manage blog-content and images. But in wp-admin, when I try to view Featured Image from Media Library, it just keeps loading... as shown below:

And when I upload a new image, it gets uploaded but it isn't shown under Featured Image tab and even not on Blog. So neither, a new image gets uploaded nor old images are visible!

How to resolve the issue, to upload an image as featured image in "Wordpress".

Note: gone through this Post, but it talks about image size.