[NEEDS INPUT] Floors glitching when placing stairs [ Edited ]

[OrlyonokOfSweden]

Product: The Sims 4
Platform:PC
Which language are you playing the game in? Svenska
How often does the bug occur? Often (50% - 99%)
What is your current game version number? 1.61.15.1020
What expansions, game packs, and stuff packs do you have installed? All
Steps: How can we find the bug ourselves? Play around with stairs, there is something going on with the half walls/fences that doesn't like it when you use stairs.
What happens when the bug occurs? The floor between two floors just goes missing and you can't place things on it or build more walls or anything. Also you cant put a roof sometimes, only if you cheat it and build it on the side of the top room and then drag it whit the size arrows to where you want it to be. If you put it on the accrual room it will either end up on the ground downstairs, or behind the house on the ground. It kind of glitches depending on the angle of your camera, but always disappears when you hover over the stairs or if you try putting in more walls or furniture.
What do you expect to see? A floor
Have you installed any customization with the game, e.g. Custom Content or Mods? Not now. I've removed them.
Did this issue appear after a specific patch or change you made to your system? No

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This bug might have come around the release of Island Living, but I'm not 100% sure.