Lots disappearing each time I start the game.

ebe88​  Please create a new save, place one of your builds one one lot, load another lot and place a single item (like a chair) that you can look for later; choose a lot where you don't have any particular build you want to use.  Save, quit, and restart your computer.  Reload this save and see whether your build is still there as well as the item on the other lot.

If your build is still present, try adding one more build and saving/quitting/reloading, then one more, until either you've added all the builds or they disappear.  If and when they do disappear, let me know how many you were able to place and whether the other item is still present as well.

You can also test the build that triggered the disappearances separately, as in, new save and no other modifications.  It's possible this build is corrupting your save somehow.  If it is, let me know what lot type it is (residential regular, rental, some kind of business) and whether there's anything special about it.

Your saves all look fine, but small, like they don't have much data yet.  I'm not sure whether that's normal for a save with new builds but without played sims—mine are all larger, but they also all have at least one played sim, so it's not a valid comparison.

Thank you for taking the time to show me the way! But I'm a veeery impatient person, so I have just uninstalled the whole game and reinstalling it as I write to you. :) Hopefully the problem won't continue. Thank you again!🙏