I'm having a problem with setting filter value from the URL. What I want to do is to list all terms in a taxonomy node, so I list all terms whose parent ID equals what's provided by URL. I have the relation set, I have the contextual filter set, but unfortunately when I enter %1 as the parent term ID value to be matched by the filter, it's treated literally and returns nothing. That's because no term has the ID of '%1'. However, when I expose the filter and type in the term ID, works as expected.
How do I use the placeholders in the filter definition?