CONTENTdm
The resource URL for expanded view images differs from that of the image record page. It is calling the IIIF version of the image so users can manipulate the display. For sites that have a custom domain enabled, the IIIF image link instead uses the system-assigned domain.
While proxying the resource, both the custom and system-assigned domains need to be configured for access through the proxy. Contact your proxy service administrator to confirm this has been configured correctly. For OCLC-hosted EZproxy members, contact OCLC Support and provide your CONTENTdm site ID and EZproxy domain.