Very weird. There must be some kind of bug. Can you go to components/com_grid/GridBuilder.php line 66 and set $debug variable to true? It will output the current query on the frontend. Now you are able to test this queries in PhpMyAdmin for example.
You can also provide me with access data to your page and I will check it out. You can contact me on This email address is being protected from spambots. You need JavaScript enabled to view it.
