https://pub.orcid.org/v2.0/0000-0003-4654-1403/works
The reason is that for some works the citation is very large, and contains several hundred authors.
So, if you really need the citation you have to do another call to get the full work data, for example as follows.
https://pub.orcid.org/v2.0/0000-0003-4654-1403/work/9761672
If you need to get multiple full works in one call you can use the 'Multiple Works' call described in the following document.
https://github.com/ORCID/ORCID-Source/tree/master/orcid-model/src/main/resources/record_2.0
Best regards,
Will