Can not disable link image when there is no link image!

Hi Support

I am attempting to insert this link here:

https://vimeo.com/help/faq/managing-your-videos/captions-and-subtitles#what-caption-and-subtitle-file-formats-does-vimeo-support

into a blog post here:

http://finalbug.net/blog/entry/547-fcp-x-subtitles-the-missing-manual-part-02
(only viewable as an admin)

But I end up seeing a broken image link.
And can not disable the image link in the Block settings on the right hand side.

I can disable the link image on another link in the same article.
Where an image got pulled successfully from a Site.

Please advise

Paul