Seems like a good place for this from the wsj:
Chinese officials and scientists provided their own extensive summaries and analysis of data on the cases, said the WHO team members. They also supplied aggregated data and analysis on retrospective searches through medical records in the months before the Wuhan outbreak was identified, saying that they had found no evidence of the virus.
But the WHO team wasn’t allowed to view the raw underlying data on those retrospective studies, which could allow them to conduct their own analysis on how early and how extensively the virus began to spread in China, the team members said. Member states typically provide such data—anonymized, but disaggregated so investigators can see all other relevant details on each case—as part of WHO investigations, said team members.
“They showed us a couple of examples, but that’s not the same as doing all of them, which is standard epidemiological investigation,” said Dominic Dwyer, an Australian microbiologist on the WHO team. “So then, you know, the interpretation of that data becomes more limited from our point of view, although the other side might see it as being quite good.”
China’s National Health Commission and foreign ministry didn’t respond to requests for comment.