Are you installing from the Intuit website or from inside the 2018 program?  Whichever one you used, I would try the other one.  I just opened 2019 and signed in on the same sign in page as in earlier years.  When you are desperate, it is worth trying all sorts of strange things....When I first installed the program it did not setup the icon as it always has in the past, so I go to the magnifying glass in the lower left hand corner of the screen, click on it, type 2019 ,
and then click on the Pro Series icon that appears there.