Problem thumbnail images

Good morning, I am using the newsblur, congratulations, it is really well made, very customisable. However, I have noticed some problems with the thumbnail images while scrolling through the news. Some sources do not reproduce the caption images. I have tried with 5 other readers and the problem does not occur.

Here are some examples

If you enter them you will see that no image appears. How come? How can I solve this?

Can you post a screenshot of this happening?

Here are some screenshots.

Also, if you try to paste the links I posted, you will see that they do not work.