Thanks for reaching out and thank you for using BoldGrid Post and Page Builder for WordPress!
I was able to replicate your issue on a dev site and I see exactly what you mean. There’s more than likely an issue with the CDN. I went ahead and notified our Dev’s and we should have that addressed in an upcoming patch for post and page builder.
In the meantime you can visit Unplash or Flickr directly to download those same royalty free images for your site..
We do apologize for any inconvenience this issue may have caused. Please let us know if there’s anything else that we can help you with.