Well, we're back with Part 2 of the ESXi upgrade. This time, I did the research and have a solution.
Here are links to the blogs that helped guide us through the process:
https://www.thehumblelab.com/vsphere-...
https://commander614.wixsite.com/webs...
If you get through all that, you still need to add monitor.allowlegacycpu = "true" to the /etc/vmware/config file.
Enjoy and thanks again to those two bloggers for their input.