Foot Placement tries to step on vertical surfaces

Are you responsible also for the FootPlacement node? Its fantastic, but there is a possible bug with the walkable surface handling. It tries to step even on vertical surfaces. I set the sweep radius to 15.0 to make the issue show up easily.

The fix is already there in the code itself, it just wasn't applied to this use-case. From FindPlantTraceImpact():

if (!bHit)
{
    // If the hit fails, use the ground plane position and a default impact normal (negated trace direction)
    OutImpactLocationWS = PointDirectionPlaneIntersection(StartPositionWS, TraceDirectionWS, FPlane(Context.GetMovementComponentFloorLocation(), -TraceDirectionWS));
    OutImpactNormalWS = -TraceDirectionWS;
    return false;
}

OutImpactLocationWS = HitResult.ImpactPoint;
if (!Context.GetMovementComponentIsWalkable(HitResult))
{
    // If the surface hit isn't walkable, use the negated trace direction as the impact normal
    OutImpactNormalWS = -TraceDirectionWS;
    return false;
}


I just copy/paste this line also into the if (!Context.GetMovementComponentIsWalkable(HitResult)) check and it fixes it.

OutImpactLocationWS = PointDirectionPlaneIntersection(StartPositionWS, TraceDirectionWS, FPlane(Context.GetMovementComponentFloorLocation(), -TraceDirectionWS));



This does actually mean the leg 'clips' into the surface a little, so an improvement if you're interested could be to move the leg laterally in this case but not vertically