We request you to verify if the email address is correctly updated in the users profile. Go to Administration > Users > Edit the users account > Email Address section as shown in the screenshot below:-
Check in the Email Notifications section if Timesheet is waiting for approval is enabled or not as per the screenshot below:-
Check under Project Management > Open the required Project > Project Info > Client Representative section ensure the correct client representative is selected as shown in the screenshot below:-
Should the issue still persist, kindly revert back or contact the support team for assistance.