After a Bounder touches the ground, it bounces to the nearest enemy available, however, it doesn't consider any terrain changes, elevation differences, bumpers, and portals on its path, which can ruin its locked position.
While Bounder automatically homes in on an enemy tank's horizontal position after its initial bounce, it does not adjust for elevation. Instead, it retains the same height as the bounce point when attempting to hit the target. This means Bounder can miss if the enemy tank is significantly higher or lower than the terrain where it first bounced, especially if the bounder landed far away from the target tank.
Bounder only bounces up ~120 PU, so if there is any terrain between the bounder's landing point and the enemy tank that is ~120 PU or more higher than where the bounder lands, it will hit the terrain instead of the target.