Some websites protect their images and so it is possible that an image will not be parsed when creating an article card. Even if you see the image in the dashboard it may not appear on your app.
The best thing to do in this case is:
(a) Download the image first and upload it in card.
(b) Screenshot capture image area (cmd + ctrl + shift + 4) then paste to Image url section in card.
(c) Replace image or save without an image.