I'm not sure if this can be of help, but have in mind that the clipboard can have multiple types of contents. Take for example Excel. If you copy a group of cells, you can paste the text content into Notepad, but also paste a screenshot of those in Paint, having done just one Ctrl-C.
So it looks like in your case the text might have been copied to the clipboard but the image stayed, and the target app used the image content. Did you by chance try to paste afterwards in something like Notepad (where of course images can't be inserted)?
Another thought: some pages have Javascript limitation to copying stuff, I recall experiencing doing Ctrl-X and still having the previous text in the clipboard. I think the key here is exact reproduction steps, maybe related to a specific site.
