Seriously - while Comey was T-boning Hillary right before voting day on emails, no one had any idea Trump campaign was under investigation.
And a year and a half later, there's still no evidence. So apparently Comey realized without evidence maybe it shouldn't be mentioned
You are either confused or lying - there is no publicly known proof, there
is much evidence.
Starting from compaign members knowing about hacked emails, to members meeting with Russian government rep. to specifically to discuss dirt, to blatant cover-up at every turn.
Watergate took two years to play out and that with people getting caught during break-in itself. If Mueller needs 3 years to untangle this, so be it.