There was an issue with the release of Studio One 3.3.0 that was causing problems with 3rd party audio interfaces.
The issue was resolved with the release of Studio One 3.3.1 release on Tuesday Sept 6, 2016.
You can download the latest release from within Studio One by selecting the HELP menu and clicking on "Check for Updates"
or
By downloading the installer from your registered
http://my.presonus.com account.