Interactions closest matching parent selector ^ not being accepted

Has anyone else encountered the problem where the interactions selector for the closest matching parent is not being accepted as input? I’m trying to create a popup modal that is repeated a few times on the page (each with it’s own distinctive info) so I want to use this particular selector to only open the modal associated with that information. Yet, when I put it in front of the class name of the modal it refuses to accept that as input. The “ok” button or an enter button press just leaves the “edit selector” window open and as such does not change the selector.

Any way to solve this?