I am doing a bit of research on visualizing publications from a specific conference. I noticed that the first conference in the series is not searchable by the ISBN provided by the publisher. I can find the conference by its DOI, but then the proceedings publications are not part of the returned data.
If you find issues with the metadata associated with any DOI, ultimately only the publisher can correct them. Crossref can’t make changes to DOI metadata directly. However, if you’re unable to get ahold of the publisher, you can always email us at support@crossref.org and we’ll pass along your feedback to our contacts at the relevant publisher. In this case that’s Association for Computing Machinery (ACM).