Unable to Retrieve Attachments or Images from SharePoint List Using Web API

We have been developing a banner app for SharePoint but encountered an issue where we are unable to access images or attachments from the list created using the Web API.

The endpoint we used is:
https://oursharepoint.com/sites/Test/_api/web/lists/getbytitle('Banner')/items

While we can successfully access other list columns, we are unable to retrieve attachments or images through this method. Interestingly, we were able to access them on our test SharePoint site.