Skanska have spent a long and expensive time investigating. They've long gone. The report (surely) wouldn't contain anything Skanska regarded as confidential to them and the data (surely) belongs to the client, not them.
And yet, despite EH's previous public assurances to the contrary, the report hasn't been released. I've heard it suggested that ANOTHER investigation is needed and that the Skanska results were insufficient. It's pretty new technology, licensed from America so who knows if it was fully appropriate for this purpose.
Unkind people might fantasize that EH were embarrassed that they'd spent time and oodles of public money getting nowhere. That's the sort of unwarranted speculation that takes root in an atmosphere of secrecy so it would be better if things were out in the open.