I usually have that issue if my master course has a student enrollment sitting in it. Delete out the student enrollment or temporarily change the role to something else and maybe that will fix your issue. Or something else is wrong and the Agilix folk will want you to submit a ticket for it.
It looks like you have an open ticket with Agilix Support regarding this behavior which is being actively addressed.
Please see our Course Copy Limitations section in our documentation to determine if you meet the conditions that doesn't allow a derivative course copy option to be present.