[FR] Corrupted Lots/Houses disappear in saves with lots of rental units

A while ago I noticed that neighbouring lots were reverting back to default. This was then followed by an endless loading screen in one of the Chestnut Ridge neighbourhoods that I was decorating with new lots. More recently, Willow Creek has began to completely disintegrate. First of all lots started disappearing, when I tried to replace one of them I got an Error 800 which took me straight out to the main menu. Another lot I've just tried loads endlessly.

I use one to two residential lots in every world, there may be more than that in a couple of the newer ones. I never, ever use mods or CC. I download lots from the gallery but that's it. My save file is very large as I like to build my game up with detailed lots. 

I've spent so much time on this save file and I am honestly so close to quitting the game. All the money I've spent on DLC so that I can have detailed, beautiful lots, wasted. I'm so upset that I've acted entirely within the game's parameters but now my game is telling me it can't cope with that.