Read my previous post. I ended up changing your settings, and testing your form.
I may have left myself logged in and not closed the element out. That's a standard J! backend problem, when you have two different users editing things. If one (in this case me) closes a window without closing the settings out, it stays locked. You'll have to do a "Global Checkin", under the System menu.
I didn't see your thread about copying the list. It really depends what you are trying to achieve. Quite often, you can do what you need by just filtering a single list. But either way works.
If you can dig up the thread you are referring to, so I can read what your requirements are, I can give you an opinion.
-- hugh