Hi,
trying from a Wikipedia page, I got the same thing.
If text and picture are copied together, the picture is not in the system clipboard, so it won’t be pasted.
But if I copy only one picture, I can see it in the system clipboard, so it will be pasted and added as a new ressource.
Maybe I’m wrong, but I don’t think it’s a Joplin task to copy multi-files sources.