Russia's primary involvement was already red-flagged several times under President Obama but nothing was done to address the problems. I'm sure that thinking Hillary was going to clearly win made it a political hot potato to mention to Americans that Russians were meddling in the election.
Think about this critical point - we all know that President Obama knew about Russia's desire to influence our elections, but he did little to nothing to address the problem. As a matter of fact, he clearly lied about the situation in that he told Trump to quit whining about the Russians because they weren’t meddling into our election. Of course, Democrats and the mainstream media aren’t addressing his blatant lies. He didn't let us know about the problem until he had to help explain why in their opinion, Hillary lost. By the way, still no collusion but many questions have come up that the Democrats were hoping they wouldn’t have to answer.