System Font Change not applying properly

[mjw72652]

I have two ethernet networked HP laptops running side by side, both of which were upgraded simultaneously to 20H2 with all updates via in-place installs from an ISO created with the Media Creation Tool, copied to both desktops, then mounted and used to do the upgrade. After that was finished, which was accomplished without any problems, I the used the same registry script on both machines to change my system font. Here is the script, which I merged into the registry on both machines:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts]
"Segoe UI (TrueType)"=""
"Segoe UI Bold (TrueType)"=""
"Segoe UI Bold Italic (TrueType)"=""
"Segoe UI Italic (TrueType)"=""
"Segoe UI Light (TrueType)"=""
"Segoe UI Semibold (TrueType)"=""
"Segoe UI Symbol (TrueType)"=""

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes]

"Segoe UI"="Comic Sans MS"

I know the script is good, because on one machine my changed font is working properly everywhere (this machine has other problems after the install which I have asked for help on in another post. On the second machine however, the font substitution doesn't work properly (it worked fine before the upgrade). It changes the font on the desktop OK, but does not change the font in File Explorer, the start menu, title bars, or anywhere else. Moreover, I am running the Microsoft Newsbar on both machines, and the one with the font substitution problem changes the font back to Segoe UI as soon as I minimize the Newsbar. If I redo the merge, and either restart or shut down and reboot, the font on the desktop (but not in File Explorer) changes back to Comic Sans and if I minimize the Newsbar the problem reoccurs. I have looked at the Registry Key for FontSubstitutes on both, and both appear correct and identical.

Does anyone have any ideas as to why this happens on one machine only, or suggestions for a fix? This machine doesn't have any of the problems that the other machine suffers from, namely some Gadgets that worked fine before the upgrade won't work now (even though they still work fine on the machine with the font problem) and the notification area collapsing as soon as I attempt to look at a notification- I have set my Show Notifications for to five minutes).

I am probably going to try doing the in-place upgrade again on both machines, unless anyone can suggest a reason why this is not a good idea. I won't do a complete install- I have too many installed apps to make the time involved in re-installation worthwhile (Ninite and Chocolatey are of limited usefulness for me). BTW, I have found that doing updates and in-place upgrades with all USB devices temporarily disconnected solves all installation/upgrade errors that I have encountered.