Thank you for the response Chris.

What I am wondering is how I set a default ‘image’ for my posts as you seem to have done:
A screenshot of a Tweet from Chris Aldrich including a default image of Norbert Weiner
A screenshot of a Tweet from Chris Aldrich including a default image of Norbert Weiner

This occurs for my main site based on the featured image (currently running ZenPress theme), however nothing is consistently flowing through from my collect site as demonstrated by the first of the two tweets below:
The first Tweet is from my ‘Collect’ site, but the second tweet is from my main site.
The first Tweet is from my ‘Collect’ site, but the second tweet is from my main site.

Not sure if that makes any sense?