I am assuming this is an issue with the built in WebView or the MBS WebView2
Some users are reporting this error on Windows;
Microsoft Edge Can’t read and write to directory
Indicating this directory: C:\Program File (x86)\Appname\Appname.exe.WebView2\EBWebView
I am not sure if this is due to the built in HTMLViewer or possibly the WebView2MBS
This is with;
Running the app as administrator does not seem to work.
Seems to be a problem with other apps as well that use WebView2. I am assuming it is some kind of strange permissions or incorrect user issue.