That is what has been so frustrating, is that it should be just that simple. So, I have now fixed the issue, but still have questions. I had installed pro, and then later installed python using the Anaconda Distribution. I was under the impression that I could use either python installation interchangeably, right? When I setup my task I pointed my "Program/Script" text box to C:\ProgramData\Anaconda3\python.exe, which did not work. I am not sure if it is a factor, but the default location that Anaconda 3.7 installs, also happens to be within a hidden folder (ProgramData). It wasn't until I changed the "Program/Script" section of Task Scheduler to "C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3\python.exe" that it worked. All arguments were passed in without quotes, and everything is now working as expected. So why can't I execute from python.exe in the Anaconda3 folder?
Also, I am still having trouble running the workforce scripts straight from a standard Command Prompt. Each time I try to run the script from there I get an Import Error for module import_ssl (see below). Again, I haven't modified the underlying script (delete_assignments.py). Instead, I am just passing the parameters through. Any ideas on why this doesn't work? Is there something obvious that I am missing?
Anyway, thanks for all your help on this Aaron!