[GAMEPLAY] Rengar doesn't attack when invisible and taunted

I played Galio, Vs a Rengar. He uses his ult, then I use mine as he turns invisible. Then nothing happens. I tried aggain with a pink ward near. Rengar gets taunt (visible taunted animation) walks toward galio in invisible mode then stop moving when he is close enough and wait for the ult to end.

1. Rengar press R
2. Galio press R
3. The taunted cat walk towards galio,does not attack and stay invisible.