UXP Plugins Won't Install

As background of possible relevance, this past week I bought a new computer (Windows 11) and used LapLink PC Mover to transfer both data and programs, including the latest subscription version of Ps. 

Today the developer of one of the UXP plugins I use, TK8, sent out a notice that a new version was available, so I downloaded it and attempted to install it by double clicking the ccx file.  Nothing, absolutely nothing, happened, including no error messages.  And, of course, the plugin had not been installed in Ps.

I tried the following steps to troubleshoot the problem, none of which worked:

> made sure UnifiedPluginInstallerAgent.exe was installed and attempted to install the ccx file by right clicking it, scrolled down to "Look for another app ..." and followed the past to UnifiedPluginInstallerAgent.exe and clicked 'Open'

> made sure the ccx files were located on the same drive partition as Ps and the Creative Cloud Desktop application

> copied the ccx files to a new location and attempted to install them

> closed Ps and attempted to install

> rebooted several times

> temporarily suspended the anti-virus and firewall programs

> uninstalled and reinstalled the Creative Cloud Desktop application

> uninstalled and reinstalled Photoshop itself

I should also note three additional things.  First, at some point in this process -- and prior to uninstalling and reinstalling both the Creative Cloud application and Ps -- all of the UXP plugins that were installed disappeared from Ps.  Interestingly, however, the prior version of TK8 was still installed on my computer, i.e., the files were in C:\User\name\AppData\Roaming\Adobe\UXP\Plugins\External, though they did not appear in the Plugins menu in Ps.  Second, as a test I was able to successfully install and run a couple of UXP plugins I found in Marketplace in the Creative Cloud Desktop application. 

At this point, any suggestions would be greatly appreciated.  Thanks in advance.

Best,

David