Sure, I have attached the screenshot. You can lock the movement in 2 ways. If you right click the landscape actor in the scene outliner, it will be under the Transform option. Secondly, if you right click the landscape on the viewport the same menu item shows.
This option works perfectly when you turn it on. The problem is that when you leave the level and come back, it didn’t save the state. Its unchecked. On the other actors, I’ve tested, it stays on when coming back. Therefore, it seems unique to the landscape actor.
Let me know if you need anything, else!
Thanks.