Re: Sims 4 Live Mode, Build Mode AND CAS unplayable.

@Sarah_eLH1997  You already have the answer: the game works fine without mods or custom content, so the problem is one or more files in your Mods folder.  That doesn't mean you need to play without any of the content, only that you'll need to test everything and remove the broken files.  If you have a lot of content, the 50/50 method can make the process more efficient:

https://modthesims.info/wiki.php?title=Game_Help:Finding_Problem_Custom_Content#The_50.25_Method

Please keep in mind that more than one of your items may be broken, so finding one doesn't mean everything else is safe to use.

The Mod Conflict Detector is outdated, and even when it wasn't, it didn't pick up conflicts between a mod and the game, only between two or more mods.