re you question: "Is your NPrinting service account for the engine a root admin in qlik sense?" why would that matter?
If it is not Root Admin you will not be able to pass many other checks, especially those where there is an access to QSR DB required. The error for me usually appears if you are working on NPrinting which is not connected to domain controller.
cheers Lech, When applicable please mark the correct/appropriate replies as "solution" (you can mark up to 3 "solutions". Please LIKE threads if the provided solution is helpful to the problem.