Using GarageSale Version 7.0.14b4 (832), macOS Version 10.12.6 (16G1212)
The middle pane “icon view” can get “out of sync” with the “list view” when switching between list and icon views.
Select 2 listings. Select icon view. Good. Change to “list view”. Good. Add another 3rd listing to selection with <command>-click. “list view” looks Good. Change to “icon view”. BAD. Newly selected listing does not show up. Add another 4th listing to selection with <command>-click. “icon view” looks Good.