What TV are you testing on? Please select the TV Software button in the Settings page in the Gallery Widget and let me know what the Gallery and Framework version is listed.
One common mistake that developers make is that some do not navigate to the second page in the category list to view the Test Widgets category. If the pagination control at the bottom of the category lists displays 'Page 1 of 2', you can navigate to the second page by focusing in the grid or pagination control and pressing the right button navigational key. Please confirm if this addressed your problem.