I ran your current version of the code with a few problems but was only somewhat successful - that’s the good news, I suppose, and the bad news is I see the same result (no motor voltage) as you and even on my own one Neo/SparkMax flywheel simulation.
I couldn’t run your project directly due to error about something gradle missing so I copied your Java files into a new project. Your directory structure was a little different than my default so I renamed your imports and package since there aren’t many.
I discovered an idiosyncrasy (error maybe) on start simulation that the first time it doesn’t show the GUI selection list - nothing to see! The second time then the GUI and driver station list shows. This happens for all my simulation projects not just yours.
I only have one XBox so I cheated and used that for both operator and driver.
Of course, the first thing I did was add a print of what you send to curvature (the joysticks).
The bad news is I, too, see no voltage going to the simulated SparkMaxes. So I simplified and simulated one of my existing small projects of a single Neo/SparkMax for a flywheel. The real robot flywheel runs fine but like your simulation there was NO voltage going to my simulated motor.
I spent a few minutes looking for documentation or limitations on how to simulate SparkMax. Couldn’t find anything recent to help. The next step would be to try a RevRobotics example program and maybe a better documentation search since usually my errors are not reading the docs (and I do better than most).
Sorry no more time for awhile - maybe another day because today is “family” day to visit relatives and pick Pixie Crisp apples (yum).
I do wonder if this is the first time you have ever simulated a SparkMax or have you ever been successful in another project?