I archived a list but can’t see it in the Archived section in Preferences

If you wish to unarchive the list or wish to simply check which lists you’ve archived over time, you need to go back into Preferences > Security and click on "Archived". There, notice at the bottom left of the screen it says "Click the lock to make changes". If you haven’t already setup a security password, go back to "Security" and setup a pass-code which can then be used here. Once setup, you should be able to access your archived / hidden lists.