Product Feed Image Errors

Hello, I used your plugin to create a Facebook product feed as described in the plugin’s information page. However when I added the feed to Facebook Catalog, the product images are not being added and I have the following 2 errors:

No image detected in FacebookFeed (13 products affected)

Image not downloaded in FacebookFeed (72 products affected)

I have a total of 225 products in the feed and product images exist for all the products. When creating the Feed, I selected ‘main image’ for the image attribute. Will appreciate you prompt response. Thank you.