Branch Filtering / DITAVAL file (Structured FM 2022)

I'm using FM 2022, trying to apply two DITAVAL files to an XML task file within a ditamap to produce a PDF.

As I understand branch filtering, placing two ditaval files in a topicref will produce one document with two sections, each section reflecting the ditaval conditioning on the source topic. What I get is a PDF with one section showing the source topic, no conditioning applied.

Symptoms:

• I'm pretty sure my source topic is set up correctly: when I change the view using Filter by Attribute it looks right.
• I have taken the two ditaval files off the map and attempted to save it using Save as PDF (to see if I could get even one ditaval file to work) but the "Prompt for DitaVal file box is greyed out.

Here's the (FM generated) XML for my map (I've tried it this way as well as adding the same topicref twice with a different ditaval on each):

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE map PUBLIC "-//OASIS//DTD DITA 1.3 Map//EN" "technicalContent/dtd/map.dtd" [ <!-- Begin Document Specific Declarations --> <?Fm Validation Off?> <!-- End Document Specific Declarations --> ]> 
<map> 
<topicref href="phasing-rf-separator-cavities.xml" type="task" processing-role="normal"><topicmeta><navtitle>Phasing RF Separators Cavity-by-Cavity</navtitle></topicmeta> 
<ditavalref href="dv-reference-include.ditaval"><ditavalmeta> <navtitle>NO TITLE</navtitle></ditavalmeta></ditavalref></topicref> 
<topicref href="phasing-rf-separator-cavities.xml" type="task" processing-role="normal"><topicmeta><navtitle>Phasing RF Separators Cavity-by-Cavity</navtitle></topicmeta> <ditavalref href="dv-nonreference-include.ditaval"><ditavalmeta> <navtitle>NO TITLE</navtitle></ditavalmeta></ditavalref></topicref> 
</map> 

And the (FM generated) XML for one of my ditaval files:

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE val PUBLIC "-//OASIS//DTD DITA 1.3 DITAVAL//EN" "ditaval.dtd" [ ]>
<val><prop att="props" val="reference" action="include"></prop> <prop att="props" val="nonreference" action="exclude"></prop></val>

 I'm a newbie to FM, structured documents, and DITA - it's been exciting to learn - but I cannot seem to get through this wall. Please tell me I'm missing something obvious. Thanks for any help.