After working extensively with Alteryx Customer Support and lot of Googling and trial and error on my part, I have identified the cause of my R Tool issues.
Unfortunately, it was not a nice and neat licensing issue that could be quickly resolved.
No, it appears the issue has everything to do with Windows 10 for ARM.
After upgrading to a M1-powered Mac Mini, I installed Parallels Desktop 17 for Mac (the latest version). I used Parallels to create a new VM with Windows 10 for ARM as the OS. I had to use the ARM version (instead of a standard version) because the M1 chip is an ARM chip.
After installing Alteryx Designer and RInstaller (both v2021.3.1), I discovered that the R Tool did not work anymore. All of the other popular tools that I use on a daily basis work just not R.
Newer 64-bit versions of R beginning with R-4.0.3. will not run on Windows 10 for ARM. The 32-bit versions will run but that doesn’t help me (or others) since Alteryx Designer only uses the 64-bit version.
I did try to trick the latest version of Alteryx Designer (v2021.3.1) into running v4.0.2 (using an installer from CRAN) but that didn't work. I also tried to pair the latest version of Designer with an older RInstaller file that installs R-3.6.3 but that didn't work either.
My only other idea for getting R to work on Windows 10 for ARM is to revert to Alteryx Designer v2021.1.5 whose companion RInstaller file installs R-3.6.3. I haven’t tried this yet and I’m not sure I will.
So, in summary, before you make the leap to a M1-powered Mac be aware of the R Tool issue and how it might impact your Alteryx workflows.