In Moodle 3.0.2 and 3.0.5 I am able to consistently replicate the following issue.

1. I have an image in an existing label, forum, quiz question, etc. This image will have a URL with with a name like "draftfile.php/31/user/draft/988999395/file.png"
2. I copy that image into a new label, forum, Quiz question, etc via the ATTO editor or the Tiny MCE editor--using either WYSIWYG or the HTML view.
3. The image first displays fine in the editor, and continues to have the same file name (i.e. "draftfile.php/31/user/draft/988999395/file.png")
4. When I save the file, I just see a broken image or the image alt text.
5. Going back into the editor, I find the name has changed to "brokenfile.php#/31/user/draft/988999395/file.png"

This issue looks a lot like the previous closed issue MDL-26329.

Thank you for looking into this.