Cannot see directory structure under folders

Windows 10, desktop, Lightroom Classic (up to date). I used to be able to click the down triangle to show all my various picture folders (D:>lp>pictures> many subfolders under pictures). (Unfortunately, each subfolder has it's own catalogue, an error that I want to eventually correct.) Previously, to move a pic from one folder to another, I could drag the pic from the currently displayed folder contents into another folder in the directory structure which I could reveal/expand by clicking on the triangle icon(s). Now, I can't drag a pic into a different folder because I can't get the "pictures" subfolders to show. "Show Subfolders" option is selected. How do I display the directory structure under the Lightroom Folders menu so that I can move images? Thank you!