While viewing a single image (ie. not browsing a directory nor in full screen view), if you click on any directory in the sidebar, the image you were looking at is removed but the viewing pane remains gray, probably because the "View" mode is still enabled and nothing is selected yet in this newly selected directory.

Then, if the "Browse" mode is selected manually, sub-directories (if any) are shown in a mostly random order. If you stay in "Browse" mode, clicking to another directory and coming back restores the correct order.

Propose solution: I would expect the "browse" mode to be automatically selected when clicking on a directory in the sidebar, and to make sure that the sub-directories are shown in the correct order depending on the user preference (View > Sort By)..