Images not displaying in posts.

OK, as the topic says, I am having difficulties seeing the images that are in posts. There’s just the empty space I see, the size of the image itself.

The weird thing though is that sometimes as soon as I post a new post, at first I can see the image, but later when I reload the page I get the result described above.

And what’s even weirder is that other people actually see the images fine. They report no problems. Even from my brother’s pc it’s all ok.

So should I be worried, or is there a simple fix, an option that I’ve missed ?

PS I know my html code is fine, as I’m not a beginner at coding.