Unifi 7.2.94 on MacOS Error When Saving Settings

After finally getting around to patching my mac mini, everything came up except for the Unifi network application. So, I downloaded the latest version and it failed to start up, so I uninstalled and reinstalled the application (Unifi 7.2.94 on MacOS Catalina 10.15.7) from https://www.ui.com/download-software/

After restoring from a backup, I tried to make the backups run weekly, and got an error message when trying to save settings

An error occurred when applying changes to System settings. This action could not be completed. Please ensure you've entered all information correctly.

Removed, reinstalled application and Java

Java install instructions from https://community.ui.com/questions/Shell-script-for-adding-Java-RE-path-to-local-UniFi-controller-on-macOS/adb1194c-cca4-4a50-8e79-cf805fdd70b3 but Java temurin8 is no longer available so used openjdk@8

$ brew install openjdk@8
$ sudo ln -s /Library/Java/JavaVirtualMachines/openjdk-8.jdk/ /Applications/UniFi.app/Contents/PlugIns/ 
$ sudo /usr/libexec/PlistBuddy -c "Add :JVMRuntime string 'openjdk-8.jdk'" /Applications/UniFi.app/Contents/Info.plist

That didn't help, but the genius in this Ubiquiti Unifi forum link - https://community.ui.com/questions/Cannot-change-save-system-settings-Unifi-Network-on-cloudkey-gen-2-pro/916daacb-39cc-4ecf-a09a-c07fee7cc23d was a cloud key error, but the solution was the same:

Switch back to Legacy Interface (Settings > System > Legacy System > Enable), make any change, then switch back to new Interface (Settings > User Interface > New User Interface > Apply Changes)

Thanks to Corey Quinn for motivating me to publish this just in case anyone else out there has this same problem - https://www.lastweekinaws.com/blog/the-harrowing-search-for-the-elusive-technical-answer/