If this issue has suddenly occured, it maybe due to a temporary server outage. You can see the current ststaus of MATLAB services at the following website: https://status.mathworks.com/
Please check if the MATLAB Online service was down during the time of the issue.
As an alternative, you can also try using a different browser, example Google Chrome/Mozilla Firefox. As per the official documentation it is recommended to use Google Chrome. Please refer to the following documentation for a better understanding:https://www.mathworks.com/support/requirements/browser-requirements.html