Jax vs Vayne Bug?

Alright folks, in a very recent game I was playing as Jax. In a team fight I had to back off because my health was getting too low. As I did so I saw vayne with little to no health and knew that one leap strike would kill her, so I started moving towards her. I also knew she is ranged so I went to use my counter strike to get me in range without taking her auto damage and found out quickly that counter strike does not dodge vaynes autos. So is this a bug or is there something I am over looking? I know her silver stacks should not be blocked, especially after three stacks, but I took full auto damage for four attacks and died. Upon checking my death recap it confirmed that I took damage from her autos and silver stacks. So let me know your thoughts or experiences on this. Thank you!!