FILEman "Gallery" menu option displays folders, but not files.

I'm trying to use FILEman via a menu item using the "gallery" type option. On the frontend, it displays all the folders in the root folder, but when you click on one of the folders, it does not display the files inside. On the other hand, the "Table" option does work properly - clicking on the folder name then shows a list of the files inside.