I am using latest auth0-react lib. After user logs in using universal login and database connection, getAccessTokenSilently, this trows error Login required. Everything works in chrome incognito mode. Same errors is Safari, Safari incognito mode. Seems to be related to cookies being blocked. It might be solved by using custom domain, are the solution for default auth0 domains? + Login Required seems to be confusing message in this case.
Did you get any responses? I am facing similar problem.
I am having the same issue. getAccessTokenSilently works in chrome and firefox