Hi! We're not really prepared to troubleshoot why that's happening with Discord (we'd just be googling it...) but you can try A) copying the link and sending it to a cooperative friend via DM, so that you can click it when you're already in the app or B) scroll to the bottom of your server list, click the "+" that says "Join a server" when you hover over it, and then click the "Have an invite already? Join a server" button. This will bring up a field where you can paste the invite link to join.