Hi @apollo13,
Are you using the latest spacedesk Driver? if not please update your driver to the latest version.
sometimes, reinstalling spacedesk Driver and viewer app fixes this problem, could you pelase try it?
also, do you maybe have Nvidia ShadowPlay installed on your machine?
Could you please check for any incompatible software, just run the spacedesk Driver Console -> Diagnostics -> Incompatible Software Products. if there is, please uninstall or disable it and try again with spacedesk