New Object Mesh Issue

Hi! This is a common mistake and it's caused by the incorrect placement of the UV map. For Sims 4 EA mapped all the CAS items into a single composition image. This mean, that for loading faster porpouses every CAS type has it's own place in a big uv map (2048x1024). When the game renders, gets the part of each item and put it all together in one image for the sim to use.

There's a template HERE that shows what part of the map is specific for each type of item. For example, earrings have their own space, clothing, hats, etc. This areas might be smaller or bigger depeding on the type. Clothing have the biggest space because it's one of the most important things in the sim body. Earrings have such a tiny space to use. This causes that really detailed earring meshes cannot be done without loosing quality. This is mostly a problem because things cannot intersect in the uv map, or the textures will bleed out in others meshes the sim is wearing.

In your example, the book is displaying the part of the body because its uv is intersecting with the uv of EA's skin.
The easiest way to fix this is to import the uv templates I linked above to blender and relocate the uv map in an area you find useful. For example, a used are is the "hats" part of the uv. This will cause that your sim won't be able to use hat if they use the pose accessory but the area is relatively large compared to others so you won't loose too much quality.

This means you need also to relocate the images of your diffuse, bump (if needed) and specular. As they all need the same requirements. Once you moved the uv map to the correct place. Export a uv layout to a 2d editor so you can ajust the Ea's original book diffuse to match.

If all this sounds confusing, post the .package and .blend file and I (or someone else) can take a look and guide you with some pics.