Filter error with UserPrincipleName ()

Hello Community Experts,

I am trying to create a report where users see there own data and no one elses. Trying to use RLS with UserPrincipleName. The role equation is [Email] = USERPRINCIPLENAME (). Attempts to save this statement gets a Filter Error -

I checked with the local Power BI SME as well as on the web, but we could not come up with a solution. If quotes are added around USERPRINCIPLENAME (), the error message goes away, but I don't think that is the right syntax. Any help is appreciated. Thanks in advance