Security blocks XML files from accessing local XSLT files in the same directory.
Issue is under investigation.
Current workaround is to start MS Edge using the following command:
"C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe" --allow-file-access-from-files "file:///[path to folder containing AOM files]/Advantage.xml"
Microsoft Edge must have the "Allow sites to be reloaded in Internet Explorer mode (IE mode)" set to Allow, in Settings, Default Browser.