Thank you very much for sending the diagnostic logs.
splashtop Windows 7 legacy WDDM driver (lci_proxykmd) is still installed on your Primary Machine.
splashtop Wired XDisplay seems to leave garbage behind.
splashtop Wired XDisplay seems to fail uninstalling their Windows 7 legacy WDDM driver on Windows 10.
Funny: Why does splashtop WiredXDisplay even install such a broken Windows 7 legacy WDDM driver on Windows 10 in the first place? Their own product isn’t even using it…
To remove this left behind splashtop Windows 7 legacy driver on Windows 10, just run Command Prompt as Administrator then type the command:
sc delete lci_proxykmd press enter
Then reboot your primary machine and try again with spacedesk.