Worlds Missing Background Buildings And Landscaping

@XxXVladimirXxX  To be clear, have you tried a brand-new save immediately after reinstalling Sims 4 and with no mods or custom content present?  If not, please try this now.  A previous incomplete install could have corrupted any saves you currently have, as could a bad mod, so it's important to cover everything at the same time.

If this doesn't or didn't help, what antivirus do you use?  And where is Sims 4 installed?  Please list the full file path you see in your EA App game library, under Sims 4 > Manage > View properties:

Please also let me know if the game is installed on an external drive/USB stick or SD card, and if you're using an external or USB, how it's formatted.

Yes, I did try that a few times before and also tried it again the last time I reinstalled it which was like an hour before I made the post and the file install location is D:\The Sims 4 which is my PC's second local disk the main big one and I will say I've always installed it there in the past with no problems. 

Btw I was looking at my game before you replied to me and the tool mod is now working too so yeah even more reason why this is odd. 

@XxXVladimirXxX  For just one affected world, please try deleting and reinstalling the corresponding pack.  First, clear the EA App's cache (again):

https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/

Make sure the App is closed and the EABackgroundService is NOT running in the Task Manager.  Go into the game's program files, here:

D:\The Sims 4

and delete the appropriate folder.  For example, Island Living's folder is EP07 because it was the seventh expansion released.  Then open the Delta folder and delete the folder with that same name; this holds patch data for that pack.  Repair the game in the EA App (again), and download that pack.

Move the existing Sims 4 user folder to the desktop (again), launch the game, create a new save, and see whether the buildings from that pack's world are back.

I did everything you said even though it did take a bit because I own almost every pack and we all know how annoying the app can be only it didn't work... 😞

@XxXVladimirXxX  Please uninstall Sims 4 and the EA App with Revo Uninstaller (the free version is fine).  Start with Sims 4:

• Put aside your Sims 4 folder in Documents\Electronic Arts and rename it to something that doesn't include the words "Sims 4."
• Download Revo Uninstaller (the free version is fine) from here.
• Launch Revo, select Sims 4 from the list, and click Uninstall.
• Cancel the system restore point; you don't need it.
• Once the game is uninstalled, select "Moderate" under "scanning modes," and click Scan.
• Review the list, in case there's something you want to save; otherwise, click Select All, and then Delete.
• Close Revo, and restart your computer.

For the EA App:

• Launch Revo, select the App, and click Uninstall.
• Cancel the system restore point.
• The EA App may open a window.  Click Uninstall, then in the Revo window, click Moderate under Scanning modes, and click Scan.
• Revo will present a list of registry entries.  Click Select All, then Delete: you don't need or want to preserve these entries.
• For the leftover files and folders, click Select All, review the list and deselect anything you'd like to keep (this is unlikely, but it's worth checking), click Delete, and you're done.
• Close Revo, and restart your computer.

Create a new admin Windows account, a local one, as in, don't link it with your Microsoft account, and sign into that rather than your main account.  Install the EA App, then create a new folder into which you'll install Sims 4.  The folder should be on the root level of the drive of your choice, for example C:\Games is fine, but not C:\Program Files\Games.

Please deselect all packs and then select only one affected one, then test the game once that pack is installed.  The EA App will start downloading the other packs once you quit again, but you can pause (not cancel) the current download to avoid everything reinstalling before you're ready.  If this doesn't help, you can leave the download paused while we figure out the next move.