I have installed the script you have provided. I can get the Firestudio mobile to work for a while by disconnecting my cable with adapter from firewire 800 to thunderbolt2 and then an adapter from TB2 to TB3, then reconnecting. However, once I have a connection and can record I lose the connection when I close out of Garageband and try using it the next time. Then I uninstall and reinstall and the process repeats. Each time the same problem occurs. The problem is I don't have a lasting connection. Any ideas on what the problem is? Thank you for any assistance.
My guess is that at this date months after the issue has been posted by others using firestudio and Catalina, Presonus does not intend to fix the problem.