Scholix[0] is a collaboration between a few orgs, including Crossref (DOI registration agency for scholarly content, e.g. articles) and DataCite (DOI registration agency for data sets).
If a DataCite member registers a data set, and mentions a link to a Crossref DOI, that's almost certainly a dataset-article link. Vice versa.
So the data in Scholix is the union of "what citations do article publishers and dataset publishers think exist".
We're working on improving how we process the data citation data, but ultimatley can't improve on what Publishers provide.
Sorry, a bit of a non-answer.
The https link doesn't work for me, working link: http://www.scholix.org/
Just now I tried searching Scholix via the web interface for IDs that are linked in Dryad, which is supposed to use the same linking system, and in either direction came up empty.
TIA for any clues!