[NEEDS SAVES] Issue with placing stairs in a basement when raising foundation

When ever I go to put a basement in my sims house, I get this-

Randomly found this in my sims bathroom-

Ever since the update and even the update to fix hotpatche from that update! HUGE issues!!

@Elithian87 

Do you have Mods or CC (or have you ever had them)? If you do please remove them in this process and try the troubleshooting as described below. (If you don't have Mods or CC, just skip the part about removing the Mods folder, but still delete the cache file mentioned and run the repair.) If you ever had Mods or CC in the past then do the steps as if you have them currently (removing the Mods folder), as there could be damage that has remained after you removed them.

• Exit your game then exit Origin. Please drag the Mods folder from your 'The Sims 4' folder onto your desktop (for future reference) then delete the localthumbcache.package file in your 'The Sims 4' folder. (When you restart the game it will automatically create a new Mods folder.)
• Next please run a game repair [ Open Origin, click 'Game Library' then right-click Sims 4 > Repair Game ]. Make sure to let it run until it has completed all repairs (it will do the base-game first, then run through each of your expansions/packs). After that, please see if the issue has stopped.

If it was Mods/CC: If this fixes the issue I would recommend that you check with the Mod and CC creators to see if there are any known issues with their Mod/CC clashing with the recent update and if so do they have an updated Mod/CC that will address the changes in the game's code from the update. You can then re-add your updated Mods/CC one at a time to see if one was conflicting with the function/causing the glitch - but do not re-add the old Resource.cfg file from the old mods folder, as it’s possible for it to have become corrupted.

If you have a lot of Mods or CC you can do so by via the 50/50 method. Let me know if you need directions on this.

When I have a foundation and I want to put in stairs to a basement. It causes a huge issue where I can't place stairs without the foundation being broken. This has been there since Eco and up mini update before it.If you add a remove the flooring/ceiling from the fenced part is the huge issues! PLEASE Fix this ASAP!!!!!!!!!!

I don't use mods 1 bit. I'm actually not a fan of them one bit. I'm repaired my game and it still caused the issue. It is clearly a bug in my book. I'll repair my game a few times and see if that fixes it. If it doesn't fix it after probably the 5th repair then you need to fix this ASAP. Please try this yourself though in your game. I feel it is an actual bug since the tiny update before Eco release. I own all packs.

The game had an update and the bug is still there I dd as requested and uploaded a lot to show the problem of a main floor to basement bug report, To find me on the gallery look up Elithian87 and the name of the lot is Oakenstead. Its the 50 by 50 lot but it does it to every lot. It is just the stair issue ONLY the stair issue!

Product: The Sims 4
Platform:Mac
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? 1.65.70.1220
What expansions, game packs, and stuff packs do you have installed? All.
Steps: How can we find the bug ourselves? Build a regular room and a basement underneath. Raise the foundation. Create fenced-off room inside the ground floor room and remove the floor, then remove the basement ceiling to make the area open to the basement. Try placing stairs to the ground floor (or ladder) within the fenced off area so the top of them leads to the ground floor.
What happens when the bug occurs? The error message "Incompatible with Terrain Constraint Block" appears and the stairs can't be placed. Also, while the foundation appears intact from the outside, it's invisible/see-through from the inside.
What do you expect to see? The stairs to connect the basement with the ground floor. And the foundation to be solid.
Have you installed any customization with the game, e.g. Custom Content or Mods? Never used.
Did this issue appear after a specific patch or change you made to your system? Neutral/Not Sure 

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Adding pics of the issue: 

I have an open space into the basement, which required not only removed floor of the fenced off area but also removed basement ceiling. While the ground floor is level with terrain, I can place stairs from the basement leading up to it (as well as a ladder). On the right you can see stairs placed with no open area. 

When I raise the foundation: 

The ladder works fine, the stairs on the right work fine, but the stairs within the open area get deleted and cannot be placed again. 

This happens in all the area, not just next to the outside wall. 

Also, with the foundation up, on the outside wall it disappears when the area is fenced off as below. 

I have tried this with multiple foundations, even flat ones that shouldn't be in the way of the stairs. The ladder works as expected but the stairs do not. 

@simmyfroggy 

I took a look at this in a test build and got the same thing to happen.  The error I got when I tried placing the stairs was Incompatible with Terrain Constraint Block.  Ladders worked fine but stairs wouldn't.  So I agree with you that it is either a bug or a design oversight since it does work if the first level is flat to the ground.  It should work if the foundation is raised too.  

What I found really odd was that I could place a stair from the basement that ran through the hole in the floor to the 2nd level above the basement but not from the basement to the 1st level.  So I can build a 2 story stair but not a 1 story stair from the basement.

Hope this helps.