Replace claims id to just get email in Nintex Form

I am trying to use the Nintex Form Replace function to get the email out of a people field

Replace(fieldName, "i:0#.f|membership|","")

When I apply it to this (i:0#.f|membership|user@email.com) I get this (||user@email.com).

So obviously it is using regex.  However if I add the escape backslashes in front of the two pipes, it still doenst work.

Anyone have this working or know how to make it work?