The cause of that is that there are microdivots in the landscape… and that the track collision mesh has sharp edges.
When two sharp angled surfaces meet each other, and they’re both unmodifiable… the inevitable result is the object itself getting popped up like that to mitigate the forces involved.
Unfortunately, the game doesn’t do the best job of signalling this point.
The easiest way to improve the issue (although it doesn’t fix it completely) is to use a capsule for the tank treads collision mesh, rather than the generated version or a box.
The bigger the capsule, the more forgiving its movement over microdivots. If it’s bigger than the width of the tracks, you can go to the tank itself and set the tracks collision response to world static only, which will make it so that only the terrain can affect or interact with the tracks - which means you can’t get hit in the larger than your track appears capsule.
For further improvements, check out L-Tecs post on suspension system. Which can be tackled after the section IMO - as Ben will still be modifying the movement system before then.