After extensive testing with several people, I've been able to determine that the problem is browser-related, and not an issue with the server.
The issue is correlated to the browser used, regardless of what server platform AEM is deployed on:
1) Chrome, Firefox, or Edge on Windows, same problem.
2) AEM on a Linux server or a Windows server, browser on Windows, same problem.
3) Chrome browser on MacOS, or Internet Explorer on Windows = NO PROBLEM!