Mods/cc may cause this issue. When you next want to delete a lot, if you use mofs/cc,try moving the whole mods folder to another place, delete the localthumbcache.package and then test to see if the issue remains without mods/cc there.
The issue may also occur if the lot had a lot of furnishings and also depending on the size of the lot.
Well, before the update I actually have done deleting lots in build mode already and it went quite well. It's just this time that I have updated my game with the latest patch and the game suddenly does this.
