Reshade working only over PART of the game display

Hi all. Currently I am using the most recent version of Reshade (4.9.1) and I have been having no issues until recently running it with Sims 4 (the only game I use it with) where it looks like it's working at a smaller resolution than my game display or it might be trying to work over a split screen.  I uninstalled, repaired my game and took out all mods just in case that might have somehow been affecting it, then reinstalled Reshade and the exact same problem occurred. I even changed my Windows settings to have everything on a single monitor (I use three) to see if that would make a difference.  Any hints as to what I can do to sort this out - am I missing a setting somewhere? I am at a loss.