Since 13 March we have experienced a technical issue meaning that events collected have not appeared in the Event Data API. We have identified the problem and the missing events will appear soon.
In better news, in the coming weeks we will be updating the Crossref agent which collects events from metadata submitted by Crossref members. The first part of the update will add events from relationship metadata between DOI records, e.g. articles to preprints, books to reviews, articles to datasets. Future work will address other relationship types, such as articles to identifiers (from Genbank, Protein Databank, etc.), and better support for data citations in references. Keep an eye here and on our blog for future announcements.