I am using windows 11 currently, and FDM windows does not get displayed on the desktop. you can see its running in the taskbar, but the program is not usable.

Has anyone experienced this as well?

It's working here fine, but it has opened off screen for me a couple of times.

Try this:

1. Open the application, and do not click the mouse anywhere after opening.
2. Press [ALT] + [SPACE] on your keyboard, then press [M].
3. Press any of the arrow keys on your keyboard to make the window appear on your desktop *somewhere*.

See if that helps.