Thank you, Klas, for the tip. Tried both options (one w/ Default in Hidden position and one with Hidden variation in Mainbody position) - neither one works. Also tried "Is Not Null", "Is Not Empty", "Is Empty" ... none of these seem to work.
I was able to come up with a work-around for my use case but still would like to understand how to make these above Match options to work. Is that a bug? Anyone else able to successfully use these for filtering?
Thanks much, P