On your screenshot, there is a mouse cursor. Were you able to move it around?
Did you also try to move a window to the extended display?
Do you have another client machine where you can try to connect and extend?
For further analysis, please send us the diagnostic logs for this issue:
– open the spacedesk Console window app by clicking the spacedesk tray icon on your task bar’s notification area
– click the Diagnostics on the left side panel
– if Debug View is not available, please click the download button first
– switch Diagnostic Collection ON
– connect your viewer app and reproduce the issue
– switch Diagnostic Collection OFF
– click Save All Information button
PS: Saving all information will take a few seconds, then please send us the whole folder which contains all the diagnostic logs collected.
Please right-click the folder -> Send to -> Compressed (zipped) folder, then attach the *.zip file on your next reply.