Setting and sorting group headers

I have a simple view with 3 fields. One is a taxonomy reference field, which I need to use as my group1 header.

However, setting that field in format settings doesn't work unless I set the field to rewrite and use its field token in the replacement text box.

Perhaps related, the view's sort mechanism doesn't work on the headers, so I'm unable to alphabetize them. There are a couple of related 6.0 issues → but nothing I can find since.

Is there a workaround?