To get flickr images to show up in the post you have to use the img url for it. Easiest way to do that is to right click> inspect the image, and copy the og img url which looks about like this
https://c1.staticflickr.com/5/4622/40035667461_d7ddf40229_b.jpg
that url will embed into the post like this
https://c1.staticflickr.com/5/4622/40035667461_d7ddf40229_b.jpg
that url will embed into the post like this
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