Thread:Project:Support desk/DEFAULTSORT in templates

This week I noticed something odd about the way that the magic word "Defaultsort" behaves in templates. I've long been using template parameters to handle this as follows

Sometimes it works, but sometimes the syntax is simply ignored. It may be that the problem occurs with diacritics only (like é, ó, í, which I use an awful lot). Manual replacement solves it but seems a bit much to ask for 400+ pages.

Is this is a known issue? Is there a way to fix it?