Secondary User Account emails cannot be accessed

A Secondary User on my account cannot access their emails through Xfinity.com.  The secondary account has been active for 15+ years without an issue.  The emails addressed to their comcast.net email address are accessible on their ipad.  My emails as the primary user are accessible.  To be clear, the procedure normally used to access the secondary account emails is to log-on to the account using the secondary account username and password, then clickiing on the user icon.  This brings up the menu with the choice to "check e-mail."  After clicking on that choice, the "Welcome to Xfinity E-mail, We are now loading Your email" screen comes up and then goes back to the previous screen without any error messages.  As I stated, when I go through this as the primary account holder, there is no problem.