Nevermind.  Ugh. Been a rough week.

HL7.{PID.7} Contains CurrentDateTime("YYYYMMDD")

Close, but not quite:

This question is more than 2 1/2 years old now, but I guess I missed it when it was posted. Regardless, the issue is that "?" is the match operator that "Matches" represents, and is not part of the pattern itself. Your match pattern should not include the "?" character.

Your syntax for the match argument is wrong. You need quantifiers for the literal strings: 1P4N1":F"5N1"R"1P. This is not obvious from the documentation ... I only discovered it through experimentation.

It appears as though the expression editor expects the pattern to be a quoted string, so you'll probably need to follow the syntax for quoting strings that contain quote characters: "1P4N1"":F""5N1""R""1P"