Nate,
I can't think of why the new build isn't working, but there is another way to complete disable the automatic interpolation that is happening when zoomed out. What you need to do is close Global Mapper, then run 'regedit', then add the value 262144 (2^18) to the 'HKEY_CURRENT_USER\Software\Global Mapper\MiscOpts' value. Then when you run Global Mapper the zoomed out auto-interpolation should be disabled.
Let me know if I can be of further assistance.
Thanks,
Mike
Global Mapper Support
support@globalmapper.com