I was able to locate the issue with assistance from Mendix. What we found was a configuration setting within IIS was causing the problem. The mxclientsystem configured in IIS was pointed to a wrong version of the mdoeler which was creating the issue. The issue was corrected byt changing the following:
Once this setting was changed the application runs as expected
mxui.widget.VerticalScrollContainer
is a built-in widget of the Mendix client so this issue is not caused by custom widgets.
What do you see in the network tab of the developers tools of your browser when you navigate to your app? One of the request should be for the Mendix client system (mxui.js). Does that request succeed and result in a response of 200-something kilobytes? Do you see error messages in the Console tab?