Apple have made changes in how our drivers are installed. Please see the following for installation Issues with FireStudio Series on High Sierra Mac OSX 10.13 and on Mojave 10.14
The following addresses this issue for both OSX’s.
Answers Article: http://answers.presonus.com/27478/installed-universal-control-system-firewire-devices-showing?show=27480#a27480
Please note that the warning on the first screen shot may not show unless you uninstall and reinstall Universal Control.
When you download Universal Control please run the uninstaller and then restart your computer and then run the installer. Then you need to go to “Settings” —> “Securities & Privacy”
Now, before you click the Allow button, ensure that you "unlock" the page so that you can change these settings.
You will only have 30mins from the time you install Universal Control to give the exception required to install.