After applying the security update 2022-003 Catalina on macOS 10.15, on some machines the physical desktop is no longer visible when connecting by NoMachine. 

The same problem has been noticed also on more recent macOS versions.

In order to make the session to work correctly again, it's necessary to add NoMachine or nxnode depending on the NoMachine version in the list of allowed programs in System Preferences -> Screen Recording.

Note that the fix to this Trouble Report will require to give accessibility permissions to NoMachine or nxnode still one time, the last one. After that, the problem should not appear again.