Warlord's Bloodlust Doesn't Grant You Attack Speed At All

According to the description of Warlord's Bloodlust, Critical Strike heals you for 15% of the damage dealt and grant you 20% attack speed for 4 seconds, with a 2-second cooldown. However, after several in-game tests with Yasuo, Tryndamare and Draven, I believe that although the heal from critical strike is obvious, the attack speed never changes. There isn't any certain way to make this bug to occur because it is simply not working at all. Since I have tested it with both melee and ranged champions, I started to think maybe the attack speed boost should never be included in the description of Warlord's Bloodlust? Either way, the description doesn't match the reality now. One of them need to be fixed.

Thanks.