The issue could be due to browser cookies, refer to Unable to Connect to VMware Cloud on AWS for initial troubleshooting.
If this issue is seen only in Chrome, it is likely due to recent security enhancement on the new version of Chrome.
You can see a warning like the below on F12 dev console if it's applicable.
console/sddcs/aws/#####< SDDC ID >######/networking-and-security:1 A cookie associated with a cross-site resource at https://nsx-#-##-##-#.rp.vmwarevmc.com/ was set without the `SameSite` attribute. It has been blocked, as Chrome now only delivers cookies with cross-site requests if they are set with `SameSite=None` and `Secure`. You can review cookies in developer tools under Application>Storage>Cookies and see more details at https://www.chromestatus.com/feature/5088147346030592 and https://www.chromestatus.com/feature/5633521622188032
https://www.chromium.org/updates/same-site: Right now, the Chrome SameSite cookie default is: “None” which allows third-party cookies to track users across sites. But from February 2020, cookies will default into “SameSite=Lax”
Any cookie with the “SameSite=None” label must also have a secure flag, meaning it will only be created and sent through requests made over HTTPs. Meanwhile, the “SameSite=Strict” designation restricts cross-site sharing altogether, even between different domains that are owned by the same publisher.