I play LOL since 2 years and since than this bug stick to warwick.
many times my W pasive part when i should be speeded up if someone is low on health doesnt work. It happens at least 3 times in last 10 games. I say at least, because most of times I am able only to spot it when low on health is next to me. Globaly its harder to notice. I can put link to a match where it happens :
arround 3 minute - Xin Zhao was below 20% HP and pretty much just next to me, i belive its still possible to reviev (2 days ago)
Also the same sitiation happens sometimes if i use W, and i know enemy is near bcs i see him, im not speeded up.