A quick little JS snippet that can solve this until CF gets it fixed.
Drop this under “Tracking Code” in the footer area:
<script>
var toHide = ['1317508','1317516']; //these products will not show in the product selector. Enter their product IDs
$.each(toHide, function (index, value) {
$('[data-de-type="order2step"] input[type="radio"][value="'+value+'"][name="purchase[product_id]"]').parents('[data-cf-product-template="true"]').hide();
});
</script>
Replace the IDs above with your 3rd party product IDs and they will visually hide from the browser, but still let you track as usual in CF.
Hope that helps!