Dragging a file from the server host to the Player machine does not work in a virtual desktop session nor in a physical desktop session to a headless Linux machine. Uploading from the Player to the server works correctly.

The file is selected, pressed and held, and dragged from the file explorer to the edge of the NoMachine window where it stops. The cursor (and file) cannot go past this window.

The problem has been reproduced on Ubuntu 20.04 with desktop environment Gnome 3.36.8 running x.Org display server.