I too had bad sickness the 1st session! The 2nd session I found the motion slider and turned it to max problem solved no sickness at all then with a update you changed the movement speed and made it slower, slight sickness feeling again, so my thoughts are that when I’m sprinting it feels like I’m not moveing fast enough and leaves me feeling frustrated/sick.
Also I feel like I’m too tall or that the ground is not at ground level I’m 5ft9” and feel like I’m way over 6ft when in VR so I don’t know how small people feel when playing in VR but even when standing still I got vertigo feeling.