Inaccessible House/ Cannot Enter or Interact With House

[owodium]

Product: The Sims 4
Platform:PC
Which language are you playing the game in? English
How often does the bug occur? Every time (100%)
What is your current game version number? 1.96.397.1020
What expansions, game packs, and stuff packs do you have installed? Cottage Living (most important) Get to Work, Cats & Dogs, City Living, Get Famous, Island Living, Vampires
Steps: How can we find the bug ourselves? Own a Cow or Llama and move household to another lot (at least according to MCC it's a problem with one of these two animals, perhaps both). The lot has to have a house on it with multiple floors, I believe.
What happens when the bug occurs? There will be two versions of the cow and llama, and even when you put one of them in a barn the game alerts you to it still being in your inventory. Most crucially, you cannot interact with the house, save for the door (and that's only to lock it); you cannot go to a different floor, change the walls, or interact with anything inside the house. You cannot enter the house.
What do you expect to see? I expect my cow and llama not to be glitched and duplicated, and I expect to be able to enter the house I spent three hours making.
Have you installed any customization with the game, e.g. Custom Content or Mods? Yes
Did this issue appear after a specific patch or change you made to your system? No

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It can't be any mods because I ran a mod checker (plus MCC) and everything up to date, additionally I have added no CC or Mods since I started this save. I've tried using the page up and page down buttons and I've tried moving my sims out of the house, selling the animals and moving them back in again. I've also tried my backup saves. I would really appreciate any help or advice as this is my generations save and I'm incredibly attached to the sims and the house.

[owodium · Accepted solution]

Okay I fixed it! Turns out the save was corrupted because I moved with any animal at all. Just had to go back to the save before I moved, sell all the animals and then go on. 

[owodium]

So apparently when you own animals (I, for example, had six chickens, a llama and a cow) and move to a different lot, your save file gets corrupted. Fun! I wanted to move to a larger lot with my generations save because my sim had a set of twins with another on the way and I'd been dealing with a 30x20 for far too long. Did so, spent a few hours making a huge farm I was very proud of, and when I moved my sims onto the lot it. Didn't work. I couldn't enter the house or even see into it. The page-down and page-up buttons didn't work, and I couldn't change the walls. So then I spent three hours preparing my game, factory resetting, etc until I found out that somehow my save had been corrupted. I've fixed it by going to a save from before moving and selling the animals so I don't move with them this time, but it sure isn't going to bring back the hours I spent on that house. 

[owodium · Accepted solution]

Okay I fixed it! Turns out the save was corrupted because I moved with any animal at all. Just had to go back to the save before I moved, sell all the animals and then go on.