Re: Why doesn't Mods work in OneDrive (Sims4)
@GemmaRosaTeen Sims 4 looks for user data in the local (on your hard drive) version of Documents\Electronic Arts\The Sims 4. Sometimes the game gets successfully redirected to OneDrive, perhaps if Windows is doing the redirecting automatically, as it often does when free storage on the hard drive is low. But that's not a Sims 4 feature—if the game doesn't find the user data where it's looking, it doesn't load the data.
Is there a reason you want your Mods folder in OneDrive? If your system drive is getting full and you have a secondary drive, you could redirect the entire Sims 4 folder to the second drive using a symbolic link.