If you were like me trying to implement RLS using fields other than email, then you have come to right place.
RLS will automatically replace the value in filter for you.
Simply use the UserPrincipalName() or UserName() function on the column you want to identify users. It can be any string that can identify user.
Example: Email Id, Guid, Name etc.
Power BI automatically replace the value in the function based on the value that will be supplied to apply the security in the report.
HTH.
