Check what stopped working
If the homepage opens but a search returns nothing, shorten the title and reset the year or genre filter. If the whole page fails to load, try a fresh tab and check another website on the same connection. A saved shortcut may point to an old page.
When Watch now opens a different site
That is the expected action here: the button opens JustWatch viewing options in a new tab. Choose your country if the result looks unfamiliar. Subscription access, subtitles, and a player error after that point are handled by the service you choose.
Missing saved titles
My List is stored in this browser. Private browsing, clearing site data, or opening another browser can produce an empty list. If a save fails, the page shows a storage message. Return to the original browser profile before assuming the titles have disappeared everywhere.