Renekton's Ruthless Predator goes on Cooldown without actually using his ability.

Since 5.10 I've tried to W on Renekton and about once every few games. The W would go on CD and nothing would happen. No stun or anything. I would usually die very shortly after I try to W, but in the past the stun would still go off. This has been affecting my gameplay in lots of close situations on Renenkton and I just wanted to bring light to the problem. This is a Reddit article I found that other people had the same problem I am having.