I just ran into this and wanted to share with the community just in case anyone else an into this.
Problem: I could see my aliases but when I would try to modify them it would take me to the page where you are creating a new Alias.
Solution: It turns out Microsoft’s new Edge browser was not handling the process correctly.
I Logged back into the firewall with Chrome and I can edit the Aliases with no issue.
Hope this helps someone else out.