Vehicle anim sit hight in Qavimator related to the bike rising up and tilting?

I have a vehicles that tilts a bit and I found it is rose up under the seat. The anim seems the only thing that could cause this.. The av is on the seat but below this it is not working. On beta grid I tried the similar anim with a different hip hight...it did not rise up after sitting and goig non physical. So do I need a custom anim with various heights? Or is it some quirk since the legs of the av are pretty high up as the seat is low to the ground, maybe creating a weird bounding box that is fixed by lowering the hips in the anim? Thanks in advance for anyone who can answer this!

I suspect that the server doesn't take the animation offset into account for physics. We see what I think is an example of this when an av appears seated on top of an object, but the sit target is way down into the prim: when we stand we get ejected forcefully.

Try it animations that require different sit targets (including the default), change the sit target accordingly, and see if that makes a difference to the physics. If so, you'll need to adjust the animation's offset.