Can't autoattack for some reason?

Was playing Darius games today and in both instances, I couldn't attack. Ok. Clarifying what I just said. I could attack, but it was a bit weird. I could cast spells and everything but my AA did not proc when I rightclicked on minions. Rather, I ended up just walking instead of attacking, which cased a bit of problem. The automatic system of AA did allow me to farm, but during the duels or a jungle gank with Ekko and Diana, I was unable to hit a W when one of them dived me under the turret, which would have allowed me to slow them and probably gotten me a kill. Second game I was against Rengar and Rek'sai. I was going to attack Rek'sai (with half health) with my W so I could use my ultimate on him since he had low health, but it ended up hitting Rengar instead even though my mouse cursor was on top of Rek'sai and I was right clicking him furiously. It just seems as if Darius used the AA automatically attacking the closest thing or something.

Not sure if it's just me or a bug, but this is really preventing me from orbwalking.