Sometimes when you upload images to media library the images might not appear in the library grid. If might be accessible from the URL though. An example error is shown below.
If you are facing the problem as shown above, you can solve this problem by doing the following.
-
Go to
settings-->media -
Untick
Organize my uploads into month- and year-based foldersand save the changes.
Now, if you try you upload new images, it will start appearing in the media library grid as thumbnails.
Already uploaded images will not appear properly. You should delete those and reupload it if you want to see the thumbnails.