Why Are My Assets Keep Moving Off Map?

I have been having several issues with my assets that keep moving off the map or buildings I placed keep moving locations on the map as well. Any idea why this may be happening and how may I fix this issue? Here is a screen shot with a few assets that are now off the map. I will be replacing them again for the 3rd time. Thanks for your time and help.

what exactly do you mean by “moving”… are they moving during the game or just in the editor on editing?

Thank you for the reply. Sorry I had not informed you on that question. There are several areas, such as a ruin or my castle I am working on that will change to a different location (or get placed) on the map while in the editor. This seems to happen mostly during my build process or when I try to use the Hierarchical LOD feature in the Editor. After either one of the builds finish, I will notice that one of the places I have on my map will have been placed some where else rather than where i had it set at the first place. Last night I had the issue with my WHOLE castle moved UNDER the map a long way down. Talk about a pain to get it moved back in place from where I had it at first.