A black screen appears when connecting to a physical desktop session on Rocky Linux 9. The connection is established, mouse cursor updates correctly, and the host shows the NoMachine notification “Your desktop is currently viewed”, but the client window stays black.

From the server logs, NoMachine reports:

NXSERVER ServerPhysicalSession/ServerSendSessionsToParent: Sending 
'1000:nomachine:0:empty:desktop:aloneXserver:1932/run/user/1000/xauth_UoJisv:
f53b9891cc35ff30c45adb989ca62f9b:1:seat0:empty:unspecified:empty:1932:
unix:path=/run/user/1000/bus:1' to parent.

This issue occurs when connecting to a physical session and the desktop type is misidentified by the NoMachine server.