It looks like you may be hitting a clipping bug that has been fixed. I have placed a new build at
http://www.globalmapper.com/global_mapper10.zip with the change for you to try. Simply download that file and extract the contents into your existing v10.xx installation folder to give it a try.
If that doesn't help, you can email the data to
support@globalmapper.com and I can take a look.
Thanks,
Mike
Global Mapper Support
support@globalmapper.com