First, I had the same thing happen to me not only with treestands, but trail cameras. The camera was on a small tract of land that only I had permission to hunt. Somehow the camera walked away, but I made the landowner aware of this.
The most recent happened two years ago, went in the day after Thanksgiving for a morning shotgun hunt and couldn't find my stand. I did find my safety rope, so for that I was thankful..
Now I have a tract that I allow nobody access too. This should reduce my issues slightly