Re: [CoL] Cannot build on lot - "can't find object" error when building walls
Since you were able to save the lot to your library and placed it in another world and everything works, then it's not the lot. So have you tried bulldozing the lot and replacing it with the one in your library? That should work. I suggest you move the sims out first and enter the lot from the map in build to do it rather than go to build from live mode with sims on the lot. Don't forget to put all the collectibles, etc. into either a sim's inventory or the household inventory so you don't lose them.
Another thing you can try before replacing the lot is to move all the sims out and then check the lot to see if the problem is still there. Again, don't forget your collectibles.
I have played that lot extensively and had no problems with it at all. I did a substantial rebuild as well and had no problems while in build mode either.
Hope this helps.