Subject: As in title.
Description: As in the video below. The passenger falls off the motorbike only when the driver gets in again.
Reproducible: Almost always.
What you were doing when the bug happened: [spoiler]https://youtu.be/u1lJteRLoC4[/spoiler]
What you think caused the bug: New sync ¯\_(ツ)_/¯
I tested on PCJ-600 and the same accident.