Admin password cannot be reset if admin account is not "Admin"

I have successfully setup my JAMS instance and everything is running fine (within its limits).

However, it seems that admin account is hardcoded as admin, even though the setup asks the user for an admin account name. My admin account is called <something_else>, but when I attempt to change the password, I get this in my Nginx access log:

- - [28/Jul/2021:11:48:18 +0000] “PUT /api/admin/user HTTP/1.1” 404 2757 “https://my.jams.instance/settings” “” “-”

Note that I have shadowed sensitive data from the entry and replaced them with explanatory text in diamond brackets.

I think the 404 is caused by this part:
PUT /api/admin/user HTTP/1.1

Should be
PUT /api/<something_else>/user HTTP/1.1