Some Elements not visible (ex. voting)

Hello,

At the posts on https://fantasy-books.live, if you look, you’ll notice that the ‘thumbs’ for voting and some of the elements on the top right are blank.

The images don’t show, but if you hover over it, or click, it works.

Can you help?

This is preventing me from getting some add-on(s), as I’m worried they won’t be visible. I would really like to spruce up my comment section.

Thank You.