The UI is letting you down on this one, I'm afraid. On desktop there's no image thumbnail, and clicking the topic brings you to the comments. You have to click this spot where a thumbnail would normally be to go to the image. I'm not sure if Beehaw has thumbnails disabled or if there's some other reason it's not showing up.

You can kind of get around this by embedding the images in the post body, that way when you click on the post you at least see them there.

Edit: Here's a screenshot of what I mean.