I appreciate everyone's insight, but I'm afraid I couldn't solve the issue. I tried executing two different scripts both on slide exit and didn't produce any positive results. So if either of these scripts are successfully setting the bookmark then the LMS is overwriting it when the connection is lost.
SCORM2004_objAPI.SetValue("cmi.exit", "suspend");
and
SCORM2004_CallSetValue('cmi.location','Slide_4');
SCORM2004_CallSetValue('cmi.suspend_data','');