In Xinet Portal, when further batches of files load within the file browser beyond the initial value set for "Number of files to show per page", the shared link options for the additionally loaded files do not provide the 'Download High-Res' and 'Download FPO' options. Your users are unable to select download options from shared links.
This behavior is a known software defect (XINET-9082) that the Development Team addressed within the Xinet 2020.1.1 release.
To resolve this trouble, upgrade your installation of Xinet to 2020.1 or later. See Downloading Xinet Installers for the steps to acquire this.