[GAMEPLAY], Auto attacking through malzahar ult, malzahar ult randomly stopping.

There have been several games which I have played as Malzahar where an enemy champion might attack through his ult. Very recently, this has happened in 3 games alone today. The champions who were ulted did not have a sash, nor were they protect by shields such as morgana's. In the last two instances, I ulted a riven, who stopped her auto attack upon my ulting, then at the mid point hit me once, and then stopped again. That single hit allowed her to finish me off using her ult before I could use my auto attack to take away her 10 health left. The second instance occurred when I was fighting a kalista. Here i ulted her, and through the entire ult she was auto attacking me. The auto attacks themselves did no damage, but it was constantly laying spears on my champion, who then had them removed via kalista's ability granting her the kill. Again, none of the champions fought had a sash or its upgrade, nor where they shield in a way that could prevent me from ulting. This issue has occurred before but less frequently. Moreover, a new issue I have had to deal with is a few times now in the last few months, malzahar's ult randomly stops, typically at the very start, at first I believed that maybe i miss clicked my smart cast combo out of order and cancelled it myself. However, it happened again today and there was a prolonged delay in my combo where my ult could not have been cancelled via out of order button pressing. Again, none of the champions ulted had the appropraite items or shield to prevent my ult from occurring.