@UntotheLord I split your comment into its own thread, because the previous thread was quite old.
It's highly unlikely that you would have a mod and not know it. Unlike custom content, which can stick to downloads and get installed behind your back, mods are standalone .package files that need to be in the proper location to work. They also show up in a popup at the Main Menu. So unless you have mods with some unknown functions, you're probably fine. (If you do happen to use any NRaas mods, you don't have to worry about those.)
The more likely source of the issue is a corrupted ccmerged.package. This file resides in DCBackup, inside your TS3 game folder in Documents, and it's required to make premium content work. The easiest fix is to rebuild ccmerged and replace the old copy with the new one.
To do this, drag your entire game folder out of Documents and onto your desktop. Open the launcher to spawn a new folder, then go to the store and redownload your premium content. You don't have to download anything else, although for the oven, you may have to download Monte Vista itself again. Install all the content into your new game folder, then grab ccmerged.package from DCBackup and place it in your old game folder. You can then delete the new game folder and put the old one back in Documents\Electronic Arts.
One note about store content: It's best to download and install in batches of no more than about six items at a time; the launcher doesn't handle large amounts of data very well. Once the previous batch is installed, you can start on the next one. Worlds should be handled separately, not in a batch with anything else.
