Hi Humayon,
I have found the issue.
When I log in with your temp details I can see the file list on the admin section, when I login with my details I get the message as above and am unable to see them, so I am thinking that it is an issue with my privileges?
This is the code I have in the All Downloads Page.
<!-- wp:download-manager/packages {"items_per_page":"17","template":"link-template-calltoaction3.php"} /-->
You can see this under Text and not Visual in the editor.