I'm attempting to implement this method to create a List View button that gets the selected rows & pass them to another method, but I'm getting an error :

Illegal view ID runSelectedRules. The ID must begin with /

Are these buttons supposed to return a page reference?  If so, how to I get the list view ID to return to the page after the controller method completes?

My List View button points to this VF page:

<apex:page standardController="Replacer__c" recordSetVar="r" extensions="replacerRunAllSelectedRulesController" action="runSelectedRules">
    
</apex:page>

Which call this controller when clicked:

public with sharing class replacerRunAllSelectedRulesController{

    ApexPages.StandardSetController setCon;

    public replacerRunAllSelectedRulesController(ApexPages.StandardController controller) {
        //Not sure why this is needed...
    }//replacerRunAllSelectedRulesController

    public replacerRunAllSelectedRulesController(ApexPages.StandardSetController controller) {
        setCon=controller;
    }//replacerRunAllSelectedRulesController
    
    public PageReference runSelectedRules(){
        List<Replacer__c> selectedRules=new List<Replacer__c>();
        for(sObject s: setCon.getSelected()){
            Replacer__c r=(Replacer__c)s;
            selectedRules.add(r);
        }//for 1
        String objectName='';
        Boolean sendEmail=TRUE;
        Integer numJobsCantBeRunNow=replacerExecute.replacerQueueBatchJobs(objectName, selectedRules, sendEmail);
        
//        return ApexPages.CurrentPage();
    }//runSelectedRules
    
}//replacerRunAllSelectedRulesController

I've tried other combo's too - putting the code in the set controller init and calling init, trying to return a different page ref, trying to return no pageref, but haven't hit anything that works yet :(

I should add that in all of my iterations, the debug logs show all the code runs, but nothing actually happens (methods aren't committed?).