After further investigation:
AS of Chrome Version 30.0.1599.69 m Google has disabled loading HTTP content into the preview when you are on a secure (HTTPS) page e.g. twitter, google, facebook, etc. (
https://code.google.com/p/chromium/issues/detail?id=238484) This prevents ezLinkPreview from working on those pages with any external links. Workaround now is to use the --allow-running-insecure-content flag which reduces security.
Google's change to chrome has not left me with any options for now. You can set Chrome to run with less security using the --allow-running-insecure-content flag, but you should consider any security trade offs...