Scratch that. I've just spoken to one of our developers, who reminded me that Mac OS Catalina has a security option that's likely getting in the way. Try this:

Go to the Apple menu > System Preferences > Security and Privacy > Privacy tab. On the left, select 'Files and folders'.
Look for 'Band-in-a-Box' in the list of apps and make sure 'Removable Volumes' is checked. Then try opening Band-in-a-Box again.


I work here