Weird interactions between malz and 2 certain champions ( Why do these interactions happen )

Figured I'd talk about it cause I find it pretty odd, playing across games has usually lead to coming up on a few times where I run into a bullshit situation where the suppression apparently doesn't do it's actual job.

TL;DR for situation 1 : Zac still bouncing around during suppression and stopping ults and cc ; his jump knocking me up even though my spellshield was up.

• 1st champion: Zac

One recent game I had with malz had brought me up against a yasuo mid or something vs a zac jungle for their team. there was a few times in Zacs ganks were even though my spellshield was up, I was still being knocked up into the air and my shield dissipating mid air or when Zac would jump into a tower dive and and I would ult him the second he hit the ground, he was still bouncing up and down and knock people out of ults or animations. I thought suppressions were meant to lock the target down in place and not allow any sort of movement till after the ult is done.

**TL;DR for situation 2: Why does nocturne upon activating the ult cancel out the spellshield and still leave you targetable? why not make it pop only if he tries to ult to you. **

• 2nd champion : Nocturne

What's the point of a spellshield vs Nocturne when triggering the ult just makes it pop and he can still target you regardless. Wouldn't the correct application to the spellshield be for it to still be active during the casting on Nocturnes ult but the shield would pop only and if Nocturne selects malz as the target. Which then nocturne's ult would be canceled out by him clicking on malz to ult to him.