Did you notice any error notification on primary machine?
Please check if any of the following driver is still present on your primary machine, please run command prompt as administrator then type the following commands and check if status is RUNNING or STOPPED:
sc query ddkmd
sc query dlkmd
sc query FLxHCIv
sc query lci_proxykmd
sc query lci_proxywddm
If you get a RUNNING or STOPPED status then type this next command:
Then after executing all the commands please reboot your primary machine and try again with spacedesk.