Could you please provide some details? Which operating system (including version) are you using, and which browser (including version) are you using? Is your Bitwarden account hosted on vault.bitwarden.com, vault.bitwarden.eu, or on your own server?
Furthermore, please confirm that you are logging out by first clicking on your profile icon (#1 in the screen shot below) and then selecting “Log out” (#2 in the screen shot below) as shown below:
After logging out as shown above, clear your browser cache, shut down the browser, restart the computer, and then restart the browser. Is the Web Vault still empty when you log in again?