Today, Wednesday, August 14, 2019, the Verizon Messages app for Android has been updated from 6.8.8 to 6.9.0.
On Monday, August 12, 2019 the Verizon Message+ app for Apple iOS was updated from 3.2.1 to 3.2.2.
After updating the app and rebooting each of my affected devices, I ran my send/receive/sync tests again.
I updated my Verizon Messages failure spreadsheet matrix with the new app version numbers (appended below).
There has been ONE CHANGE to the SUCCESS/FAILURE results as tabulated in my original spreadsheet matrix.
The Windows apps now FAIL to sync to Verizon Messages on their web page.
Verizon is doing something, but sadly they have not restored, but ADDITIONALLY DAMAGED, functionality that worked for years before 19 July 2019 (at least for me).
Thanks Verizon, your Windows functionality has been flushed down the toilet!