2017.05.17 Seth Rich
There was a lot of news around Seth Rich (murdered) of being the source of the WikiLeaks emails, including inferences from Julian Assange himself. Because it didn't fit WaPo's narrative, they were mum on the whole topic. The reports at the time are likely bullshit (and have since been altered or purged), but there was more evidence for it at the time than there was for most stories WaPo was running that was blaming it on "the Russians". Even if you only report something to refute it, suppressing things you don't like is called FakeNews.