a) While the faderportv2 is powerd on: Hold the "next button" and press "Solo" for Studio One mode.
b) If you are using Studio One v3.5.x, than you need to install the faderport extension: See "Your Account/Products/Software/Extra Downloads".
b) Did you install the new versions of Universal Control [Nov 2018: v2.9.2] AND Faderportv2 firmware update [Nov 2018: v3.03]
c) Your Faderport should be included in the list of "External Devices/PreSonus", if not you can try the Faderportv2 installer. You will find the installer in "Your Account/Products/Your Harware/Faderportv2" OR maybe update/re-update with the latest Studion One v4.1.1 version.