Technically, Jumps are just stylized Dashes, as exemplified by the fact you can't jump above Zigg's minefield or Jinx's chompers. The wikia also says so.
So why are they taken into account for Yasuo's ult? He can ult Trista mid-jump, Aatrox/Kha'Zix too.
MisterHealYoGirl1 votesHe cannot ult Tristana or Kha'Zix if she's leaping. That functionality was deliberately removed. If this happened to you, it's a bug.
DeathBurst1 votesOh. Good news :) Do you have a source (patch note, red post somewhere,...)?
MisterHealYoGirl1 votesIt was removed before he was even pushed to the PBE, so no.
1374341 votesIf the knockup or displacement is self/ally inflected (e.g. Thresh Lantern, Trist/Aatrox/Kha jump, Zigg's w) an enemy yasuo can not ult to it, unless there is a bug. This was purposely done so you wouldn't be punished for using one of your abilities just because the enemy team has a Yasuo.
Yasuo can only ult enemies either he or his allies knocked up/displaced.