Why this problem is showing
This problem is showing because google changes the file directory of the image this why the custom widget of Blogger can't able to patch this image from the RSS feed of your blog. All the custom widgets of Blogger run show the image from RSS feed due to directory change this why they can't patch this image this why the image is not showing in your custom widget like read also widget.
How to fix this issue
Blogger doesn't provide us hosting Cpanel this why we can't fix this issue directly but there is a small cheat paint, Google doesn't delete the old directory when you upload an image on Blogger server it will upload on both file directory but so much people ask me where I get the old directory URL? Infect my friend there is no way to found this old directory URL but there is one more cheat point.
Fast upload your image and add it to your post now don't remove the link on this image. Just open your post HTML view now you will see the src URL and the href URL both are different.
|Both URL is different but on the URL both image are same|
Now your blog post image not showing on the custom widget problem is fixed. I hope this article is helpful for your blogging. Now if you face any problem about this article then you can contact me on contact us page and also you can comment down below.