iOS reading list doesn't work offline
Adding something to your reading list


On your desired webpage, click the share icon in the top-right


When opening something from your reading list make sure you open it at the side not in the search bar.

From this Apple Discussion:


  Once you add something to your reading list you do not access it from the URL box.  You access it from the open book icon just to the right of the URL in the upper right corner of your screen.