Hi Jacob,
Here is what you will want to do:
1. Open Studio One and go into Help>Open Settings Folder.
2. Close Studio One.
3. Inside the settings folder, there is a folder named "Extensions." Delete the mp3 Converter from the Extensions folder.
4. Restart Studio One and go into Studio One>Studio One Installation. Install the MP3 Converter once more and it should be working for you. If it is not, repeat the above steps but this time log into your my.presonus.com account and download the Converter from there. It will be under My Products>Add-ons. Double-click to install.