AddCustomFilter Not Working as Expected (Neither In-line NOR Lookup)

I have found quite a few helpful resources about the AddCustomFilter method in jScript that can help us to filter a lookup in ways that OOB CRM cannot.  I have been tackling this issue for a while, and have gone at it in a number of different ways.

Here is the requirement:
On a Work Order Product, the Product Lookup must be filtered to show only Products that belong to the PriceList which is set on the Work Order.    Using related records (OOB) filtering, I can only achieve this by using the Default Price List of a product - which will not work for my requirement.

Basically, I want the Product Lookup to only return Products that exist in the Price List that is set on the Work Order.  

Right now, I am getting *some type* of filtered list, but it isn't correct.  And further, inside the lookup window (where you can change the views, do search, etc), if I click the Magnifying Glass (Search) icon twice, the 'filter' (which again is not correct) disappears, and then a list of ALL FS Products is shown.  Why is that?

Here is my code. This is the simplest implementation I've tried over a number of attempts.  I just recently added the Try/Catch blocks, since this was so dang simple, I wasn't thinking i'd need them. But at this point, I am not catching any errors, no errors in F12 Debug, and no errors popped by CRM UI.

Any thoughts on why this his happening?

function FilterWOProductList() {
    
        var PriceList = Xrm.Page.getAttribute("msdyn_pricelist").getValue();
        //checking if pricelist fields is empty before we apply the filter
        if (PriceList != null) {
            Xrm.Page.getControl("msdyn_product").addPreSearch(Filter);
        }
    }

    function Filter() {

        var PriceListValue = Xrm.Page.getAttribute("msdyn_pricelist").getValue();
        var PriceList = Xrm.Page.getAttribute("msdyn_pricelist").getValue();
        //if PriceList has a value, proceed
        if (PriceList != null) {
            //used to retrieve Name of the Price List held in the PriceList field
            var PriceListTextValue = PriceListValue[0].name;
            //GUID used in filter (pricelist GUID)
            var PriceListID = PriceListValue[0].id;

            try {
                var plist_filter = "<filter type='and'>" + "<condition attribute='msdyn_pricelist' operator='eq'  value='" + PriceListID + "' />" + "</filter>";
                Xrm.Page.getControl("msdyn_product").addCustomFilter(plist_filter, "msdyn_product");
            }

            catch (e) {
                Xrm.Utility.alertDialog("addFilter Error: " + (e.description || e.message));
            }
        }
    }