This may be happening because the image was removed from your FTP. All images that you upload into the image library are hosted by Luminate on your site. However, the folder where the images are stored is accessible by any admin with FTP access, so if those files are accidentally removed, it will cause any link to that image to break. Here is how you can check for this:
  1. Login to your FTP
  2. Open the folders: Images > Content > Pagebuilder
  3. The Pagebuilder folder is where your image library images are stored. Check to see if there are any images with the exact file name in the URL for your image. If the image is missing, it means it was removed from the FTP. Upload a new image in that folder with the exact same file name, and that should allow your current image paths to work properly.