If you see a texture on the world model, but still not while being carried, then you would want to check the same thing on the Armor Addon, which is in the right lower quadrant of the shield form, though in my experience the shields are pretty simple, so world and carried models are usually the same one.
If not, when you find them, put them in following that file path. Try to follow that file path, within your data folder, to see if you end up where they are. If you see that but no texture is visible on the model there, I'd guess you're missing the textures themselves, or they've been installed in a different file path. You should be able to click on that and see what (if any) textures it is expecting to see.
On the right hand side, upper quadrant, there should be an edit button to change/view the world model associated with the shield. Open creation kit, find the shield(s) in question and double click to open their form. Two things you can try, if you're familiar with either option:
