Completely uninstall/reinstall Universal Control using the steps below:
>>> First, download the Universal Control 1.7.4 .dmg file: https://pae-web.presonusmusic.com/downloads/products/dmg/PreSonus_Universal_Control-174.dmg
>>> Use the Uninstaller file from the UC 1.7.4 pkg.
>>> Then click your Go menu and select Go To Folder.
>>> type or copy/paste this precisely.
>>> Click GO
>>> Find the PaeFireStudio.kext file and trash it.
>>> Then close the windows currently open.
>>> Click the Go menu again and select Go To Folder.
>>> Type or copy/paste this precisely.
>>> Find and trash these files.
>>> Empty Trash and restart
>>> Then run the UC 1.7.4 installer.
Ensure you are using the approved Thunderbolt to Firewire adapter.
Apple's Approved Thunderbolt to Firewire Adapter: https://www.apple.com/shop/product/MD464LL/A/apple-thunderbolt-to-firewire-adapter
If the issue persists, create a support ticket from your my.presonus account.