There is a limit to the amount of information that can be sent through Xero’s API (60 calls in a rolling 60 second window and 5000 calls in a rolling 24 hour window).
If you exceed this limit, the images will not go across to Xero.
To get the images to go across, simply delete the items in Xero and then republish from Receipt Bank:
1. Select the items in your Archive (tick the checkbox). You can try the 'Advanced search' engine, next to the 'Supplier search' box
2. Click the first button on the menu at the top that says "Unarchive". Ensure you select the "Clear publishing data" before submitting.
3. Republish the item from your 'Inbox' by clicking the 'Publish' button.