Please following the steps below to resolve that issue. This is removing it from inside of Studio One and installing it again and it will work.
1. Uninstall Fat Channel Collection Volume 1 from menu Studio One > Studio One Extensions and then restart Studio One.
2. Go to menu Studio One > Studio One Installation > My Purchased Items and install Fat Channel Collection Volume 1 again.
If you have any problems installing add-ons please see this support article: