Your promo-tweets are showing the same image day after day.
One of these fixes will solve or explain your problem in 99% of the cases.
1. Check the tweet text field in your paper settings. If you are promoting your paper URL here, is the paper URL typed correctly? Check that you have the full URL of your paper saved in the tweet, including the prefex https:// i.e. https://paper.li/yourpaper.
If your paper URL is typed correctly, an edition id will be added to the URL, shown below in the preview window. The edition id is necessary in order for the most updated image to show.
2. In the Tweet text field, are you promoting a URL other than your paper URL? If so, Twitter will show the image and description from your own URL source code (if you have saved one using twitter meta tags).
3. If a URL other than your paper URL is appearing in the Tweet text field and you are not sure how it appeared there, check to see if you have entered an external URL (for your blog or main website for example) in the Auto-promote redirect field in your settings.
An external URL should only be entered in the Auto-promote redirect field if you have embedded the Nomad or iframe of your paper on the site.
If this is not the case, remove the URL from the Auto-promote redirect field. Return to the main twitter toggle under Social Media Agent. Switch off and back on to reset your promotion. Your paper URL should now show in the tweet text field.
4. Be aware that if you include any other URL besides your paper URL (for example: a URL shortener or a snip.ly for your paper), the most recent "meta data" for your paper is not being sent to Twitter. This will result in Twitter displaying an incorrect image for your paper on most days.