The size of the file is over 2 GiB. Files larger than 2 GiB are not supported by the ISO9660 standard in its first and second versions (the most widespread ones).
It is recommended to use the third version of the ISO9660 standard, which is supported by most operating systems, including Linux and all versions of Windows™.
However, Mac OS X cannot read images created with version 3 of the ISO9660 standard.