I have two worlds in world anvil and switch between them regularly. After the big update however, my newer world's articles are the only ones that I can access traditionally with the article tree. When I try to switch to my older world the articles there are replaced by the folders and articles of the newer one except for the folder that I had opened last in the older world. On the surface this appears to be a Brave issue, which is my main browser, because i tried with Google and there it works fine.
Use Brave, have two worlds in world anvil, switch between them.
I have seen the same problem (using the Firefox browser). Workaround: In the article/category list, at the top where the name of the world is listed, click "..." to open the menu and click "Hard Reset". That will re-synchronize the article list with the current world.