Hi guys
Just here to talk about a weird interaction I've got in game against a Yasuo while wearing Bramble. So I tried on custom with a friend to test it out. The Q3 test start at 0:39.
It is inconsistent sometimes 
does damage and apply Grievous Wounds, sometimes it doesn't apply the debuff and sometimes it even doesn't do damage at all.
Yasuo Q will only act like an AA on the first target hit. So the first time Sol was the first and only hit and that is why bramble vest applied. The next time the 3rd Q hit Sol and didn't apply bramble vest was because you hit a minion 1st.
Meaning there is no bug here.
Yasuo's q applies on-hit effects to the first enemy hit. Bramble Vest counts as an on-hit effect, similar to Panth shield and Shen block, if they are the first enemy struck. This also occurs without the third q
