Have you done any user account switching or remote desktop connection before using spacedesk?
Could you please run services.msc on your primary machine, find spacedeskService then right-click restart it.
Then try to connect again with spacedesk viewer.
If problem still persist, please send us the following for further analysis:
- run dxdiag.exe on primary machine, click "Save All Information" then save the output file (dxdiag.txt)
- all *.etl files on C:\Users\Public\spacedesk_logs folder
Please save all the requested file in one folder, right-click then Send to -> Compressed (zipped) folder, then attach the zip file on your next reply.
Looking forward to your feedback.