Ekko doesn't use Sheen or Lich proc on his passice proc
After proc'ing his passive with a third strike, the effects of Lich Bane aren't used. It seems that the fact the passive applies spell-effects completely over-rides the identity of it being proc'ed with an auto-attack, so it cancels any on-hits. It's causing a bit of an issue as the extra damage from Lich or Sheen can mean the difference between getting a kill or getting splattered, and having to take an extra hit to apply the effect (considering that Ekko's AS is usually below 1 per second) can really screw you over.