Appointments+ shortcode [app_services order_by="duration"] not working

I am getting a lot of great stuff working here, and I'm delighted (my client will be, too), but I have the following shortcode in my form, and it's still sorting by ID.

[app_services select="<h3>How long do you need a sitter?*</h3>" order_by="duration" autorefresh="1"]

I have also tried order_by="name" and adding DESC to each. None yields any change.

I'm attaching screenshots because the pages in question are protected by Membership 2 Pro levels.