@Inez2 It's unlikely that someone from almost two years ago would respond to a tag, especially in an inactive thread. But I can try to help.
Whenever adding content to your game, it's a good idea to delete the five cache files in your TS3 game folder in Documents. If you haven't already, delete them now and test. For reference, the files are:
- CASPartCache.package
- compositorCache.package
- scriptCache.package
- simCompositorCache.package
- socialCache.package
If that doesn't help, what kind of install do you have? If it's not Origin/Windows, you may be missing the store patches that used to be offered through the launcher.
Another possibility is that you have a corrupt .ebc file in DCCache. These files are bundled store content, and a corrupt one can refuse to accept new installs, even though the launcher thinks the install process completed. It's simple but time consuming to rebuild one of those files, so please address the other issues first.