To make the creation show up correctly, you'll need the mesh that was used to make that creation. In some cases you'll also see a weird blocked texture on the Sim, with question marks on it. For clothing you'll see missing body parts. For instance for missing hairstyle meshes you'll see a bald head instead of the hair you've seen on the previews. In this case you can see the thumbnail for the creation, but it's not showing up as you would expect. * Some custom content needs a mesh (the actual shape of something like a hairstyle, clothing or object) for it show up correctly in game. Part of the CC is not showing up as expected In the Gallery settings you can change the settings to make those Lots and Sims show up as well. By default your Gallery will hide Lots and Sims that need something that is not installed. * Lots and Sims that are not showing up in your Gallery might also need a specific Pack or other custom content that is currently not installed on your computer. Having an unpatched game or a non-official version of the game will cause some CC to not show up in game. This can be the case when something is cloned that was added by one of the game patches. * Some creations will need the game to be fully updated to show up correctly. * Some CAS creations will only show up if you remove the default male/female setting in the filter. When using the CAS filters for only showing custom content, that creation should be easier to find. * Some CAS creations can be made a s recolor variation of an in game item, instead of showing up a seperate item. The description of the downloaded creation on TSR should in that case give info about what is needed. * Some custom content will need a certain Expansion, Game or Stuff Pack for it to show up in game. * Make sure your CC is placed in the right location on your computer. To make it show up again, you'll need to enable it again manually in the game settings, and restart the game after that. * After most patches the game will automatically disable the use of custom content in the game settings.

If your downloaded and installed custom content for The Sims 4 does not show up in game (or not showing up as expected), there can be various reasons for that:

Sims 4 script mods not showing up