See if anything from this KB article linked below is helpful to you. The part quoted below is from the very bottom of the KB article.
http://support.presonus.com/hc/en-us/articles/210040293--5-Installing-Additional-Content-PreSonus-Sound-Sets-
*Potential issues with Corrupted Downloaded and/or installed Sound Set files.
On occasions the installed and/or downloaded Sound Sets file can become corrupted.
If you ever get a warning on the StudioOne load screen that a sound sets has become corrupted or is not loading properly, the installed sound set can be removed from your system and then re-installed directly from the installer built into StudioOne or directly from your user account.
* It is advised that you first remove the affected sound sets file from your sound set library that is on your system before downloading and reinstalling a new instance of the sound set file on your system.
The library StudioOne scans can be found in your StudioOne software for reference. By default it will be Documents/Studio One/Sound Sets.
That file path can be found under the "StudioOne" menu --> Drop down select (PC - "Options" || Mac - "Preferences") --> "Locations" --> "Sound Sets".
*Dragging and dropping a Sound Set file onto the StudioOne start page will install that sound set to the default location set in the file path listed above.