Re: Custom Content will not show up with Sims4 on external drive
@laijahd There are two separate locations for Sims 4 content, and they need to be handled differently. The game's program files, those that Origin installs, can just be installed to the external drive, and if Sims 4 runs, you've handled that fine.
But that doesn't cover custom content, which is stored in the Documents directory. If you simply move the Sims 4 folder out of Documents\Electronic Arts. or move the Mods folder inside it, the game won't read the folder in its new location and will instead spawn a new instance of that folder, one with new content. The solution here is to create a symbolic link within the Documents directory pointing to the location of the Sims 4 folder on your external. Please see this guide for details:
From your description, I don't think you need to wipe your computer and start from scratch. However, when creating the symlink, please be very careful to get the commands exactly right—one small typo can ruin the whole process.