Zac Ult Bug

Played a game as Rakan with a Zac. I hit an enemy Lux with my charm right before Zac finished charging his ult. Zac jumps and Lux does not move with him. I linked a video of it in slow motion. You can clearly see that Zac's ult is fully charged and Lux is standing on him, but she isn't displaced to his new location.