Hi sam!
The hotlinked image isn’t downloaded. The preview is indeed created as your screenshot shows, but the link still points to the external image. There is no lightbox either. Is that because the link points to the external image?
But I see that this message of Taylor in Oni’s linked topic points toward the same issue, even if there is no onebox when you just display an image (?).
So I suppose the issue will be resolved “in the next few weeks”.
A question nonetheless: will the existing posts be fixed automatically? If not, how to update only these posts so the links point to the local image?