If you prefer to have a list rather than use the search function, you can always click on the link called "more new lessons" on the main page http://guitartricks.com/main.php. There's a sort fonction at the top and a more lesson... button at the bottom.

Clicking the more lesson fonction will list the next 25 lessons newest lesson in that categorie you've selected. If you select no category then it's going to list you the newest lessons posted.

The list is limited to 25 per page probably for performance purpose. A complete list would take a lot of time to be created due to the amount of lessons available on GT. Still I think this might be more what you are looking for.

You can do the same thing with tutorials by accessing the Lesson tab on the main page and choosing a category.

As for the search function I'm not sure what causes the issue you're having. If someone doesn't get back to you here about this issue, maybe drop a mail to support http://guitartricks.com/contact.php