It did not work on the Xperia 1 VIII XQ-GE44. #1

Steps taken:
Installed and enabled Taskbar.
Configured settings according to the Quick Start guide.
Connected an external monitor and set it to mirroring mode.
Pressed the button to enable FreeformShell's desktop mode.
Selected FreeformShell from Taskbar.
External monitor: Displays only an icon with nine dots against a black background.
Smartphone: FreeformShell appears in a floating window.

Is there a solution to this issue?