If the device isn't mounted as a real filesystem, it may be displayed via the Windows Shell's virtual folder mechanism, in which case Windows takes over most of the display and handling of what's in the folder.
With an Android device in Opus, this may also depend on if the advanced mtp_enable setting has been changed. See MTP and transferring files with Android and iOS phones, Cameras which also recommends using FTP or SFTP instead of other methods of accessing Android devices; those will always use Opus's own copy functionality, and are often more reliable as well, and allow transfers over wifi without having to plug in a USB cable.