There are various possible causes why the title isn’t appearing, and it would be best and easier if we can see the site for ourselves.
However, for debugging, you may also try #1: https://docs.generatepress.com/article/debugging-tips/
Or, if you have element set to display on this page, which should appear on the admin bar as such: https://share.getcloudapp.com/YEurEQpd, you may also try disabling these temporarily.
Also if you have custom CSS code or PHP code, try removing them temporarily as well.
It would be good to take a backup of your site before doing these.
Try clearing all caching mechanisms set on your website as well.
Hope this clarifies. Kindly let us know how it goes. 🙂