It turns out there's an error in uc_product.module. The function uc_product_views_tables_alter() should be passed the $tables array by reference, so change line 1085 to
<?php
function uc_product_views_tables_alter(&$tables){
?>Once that's saved, clear out the views cache (or at least the views_tables row) and the options should show up on the fields properly.
I'm pretty sure I had it working before, so I don't know why it would be broken now. *shrug*
Joined: 08/07/2007