The screenshot shows a number of drives in the navigator and they all have the expansion triangle next to them, so I'm not sure what the issue is. Perhaps you need to enable
Full Disk Access (it looks a bit different now on newer versions of MacOS but the concept is the same), but that setting doesn't affect whether or not drives appear in Navigator, just whether or not you can access them. If that isn't it, please provide more information about the problem.
