This issue was fixed in the July 16th, 2024 release.
issue
We are aware of an issue in the Anaplan UX where users receive the message "We can't find this page" when navigating to a page, despite the page existing and the user having sufficient access.
workaround
You might be able to access the page by trying a few different methods. Some users have had success by either refreshing the web page or going back to the previous page and clicking the link again. Alternatively, you can use the Global Navigation to return to the home page and then select the page again. Please try these steps and see which one works for you.
If these workarounds do not allow you to access a page, please contact Support at support@anaplan.com.