In a moment of (ahem) inspiration I uninstalled the 2018 program for 20 returns on my computer and downloaded & reinstalled the same program from Intuit. Amazingly that action cured my printing problems immediately. I successfully tested printing on two returns however I have yet to Net-file either of these due to final confirmation with the taxpayers to ensure that they have nothing more to disclose or add to their T1 2018. It is my untrained opinion that somethings in the program's update method did not update properly at least on my Windows 10 newer computer.
