Resolve #5895 by setting the initial mOnGround state to false; we do this because the movement solver runs one frame behind so when we run through the loop the first time we assume we are on the ground even though we may be 400 units in the air.

apps/openmw/mwphysics/actor.cpp

@@ -72,6 +72,7 @@ Actor::Actor(const MWWorld::Ptr& ptr, const Resource::BulletShape* shape, Physic
     updatePosition();
     addCollisionMask(getCollisionMask());
     updateCollisionObjectPosition();
+    mOnGround.store(false, std::memory_order_release);
 }
 
 Actor::~Actor()