The biggest issue I've encountered in Brindleton Bay (specifically the 64x64 lot) since Seasons is this:
Every time I place a building in an area in the back of the lot the floor disappears when I zoom in. But even worse is that the entire floor becomes invalid. I'm unable to change the floor, the floor cannot be bulldozed (only way to get away with it is to delete the room entirely) because the game doesn't recognize it. And items arent able to be placed directly onto it. The item doesnt center with the cursor when I attempt to move an item (the item is all the way out to the side) and recently, I'm not even able to place any objects on the porch outside, only on top of the edge of the foundation. At one point the entire lot went like this for a few minutes. I've tried taking down the buildings I build there, building new ones, bulldozing the lot, etc. It seems to be an issue with this lot alone, and I continue to have it on every save game I try and I've tried repairing the game.
Comments
I will tag @BryonyRae to see if she can assist you. She is great at testing build mode issues.
http://forums.thesims.com/en_US/discussion/817478/hello-come-and-introduce-yourself
http://tinyurl.com/OneRoomOneWeek
http://tinyurl.com/rosemow
My Showcase thread https://forums.thesims.com/en_US/discussion/948861/rosemow-s-rooms-showcase
If you still experience the issue after that, the next step would be to post some screen shots and tag me, so that I can see the exact structure(s) you have on the lot before and after adding the building in the back so that I can attempt to duplicate the issue. Currently, in my game, I'm not seeing an issue with building on the lot, but I don't have the exact details from you.