I log in and am redirected to the main page. When I try to click on a button that redirects to another page, I am thrown back to the login page and the session ends.
Do you have any details on your application?
Do you use Spring Security? If yes, is every page accessible for your logged in account? Is the session really ended or the targeted page maybe just not accesible (i.e. can you go back to the previous page that worked)?
Maybe some other special things, like load balancer, proxy, or similar?