Since I do not have the skills to evaluate the diagnostics and resolve this issue and I was not getting a lot of useful advise from the Form, I went with plan 'B'.
I am sure there was a simpler solution but I was not seeing it and it was time to get beyond this issue and get on with living. FYI, I have included the steps I used to a successful resolution. The one thing I can say about this approach is it speaks to the resiliency of the unRAID system, the Holy Grail of any NAS, no data lost.
1- From local desktop browser unRAID console went to Main -> Flash -> Flash Backup and created backup to local desktop hard drive
2- Carefully going to screens on console cutting vital information, e.g. serial number of drives assigned to which disk, name of shares and other setting, to paste into a text editor.
3- Shutdown unRAID, remove flash and place in desktop machine.
4- Copy /config/Plus1.key from flash to desktop machine
5- Using Unraid.USB.Creator.Win32-1.5.exe reload current unRAID version (6.6.6)
a. Selected Customize and added my server name
b. Selected static and provided my IP address & Allow UEFI Boot
6- Copied Plus1.key file from desktop back to /config folder in on newly re-imaged flash drive
7- After completion, ejected flash drive, inserted in server and restarted Unraid server
8- Back at unRAID console at Main screen, reassigned to Disk positions.
9- Stared Array and the system went into Parity-Check.
10- I was now able to go to /Settings/Notifications and Enable the subsystem.
11- Since I could see that all of my previous User Shares and VMs were recognized, I went to bed and slept well.
12- Today I will reload and reconfigure my Dockers and other Plugins with text copy of previous information.
Not sure how to mark this issue resolved but it is.