Third fix tried and failed: the terrain staged in the probe map with collision disabled entirely. The pawn
still rises (Z 315 -> 421), exactly as with collision enabled.
With that, the terrain's convex hull, its collision channel and its collision itself are all eliminated, and
the failure survives in a map whose only difference is the presence of a 279 m static mesh.
The player is unaffected throughout - re-checked after every attempt, still standing on Sidewalk_North_07
at 157 cm - so nothing in the walkable demo regressed.
Deferred rather than guessed, per AGENTS.md: the task is marked deferred with the three failed fixes, the
probe workflow and switches a fresh session inherits, and the next question framed precisely - why a map
containing a collisionless 279 m static mesh changes a physics body's behaviour, which points at streaming,
memory layout or the broadphase rather than at collision authoring.
Generated probe levels deleted; the tools stay.
Built the map-content bisect the task asked for: Tools/ue_vehicle_probe_map.py duplicates ReviewMap,
optionally adds one demo mesh and the pawn, and saves it as VehicleProbe.
control (no extra mesh) Z 300 -> 297 rests on the review floor
+ Terrain_DEM Z 300 -> 498 thrown upward
So Terrain_DEM alone reproduces the fault in a map that works. Two fixes were tried:
- Tools/ue_clear_simple_collision.py cleared the auto-generated convex hulls from all 76 site/street
meshes - the terrain had ONE convex element over 279 m - and set them to complex-as-simple. Still rises.
- The terrain component set to QueryOnly, so traces hit it and physics ignores it. Still rises.
Neither changed the behaviour, so the ejection is neither the convex hull nor the collision channel. The
next probe is the complex triangles themselves: give Terrain_DEM no collision at all in the probe map and
see whether the pawn falls. If it falls, the triangle winding is pushing bodies out of the ground mesh -
the same inverted-winding family that made the sidewalk unstandable earlier.
Both tools have README rows; the pawn is parked again.
zwitschi