Darius' Crippling Strike and attack movement

I have noticed since the release of 5.16 and the juggernaut changes that occasionally when I use my Crippling Strike (W) while chasing an enemy, there are times where he simply stops. Stops attacking and stops all movement. Is this intended in the change? Previously when I would cast the ability and he was auto attacking on someone, he would continue to auto attack them and simply use the ability and keep attacking. Please let me know if you could if this is the way the ability is meant to work at this time. Thanks, Riot!!! (P.S. Why the delay on Decimate??)