Thank you for the quick response. You are correct, there is a "Notify Students" option under the individual assignment settings. And that setting is accurately represented as a proper combo box with a Yes/No option rather than a checkbox like in the global plugin settings. 

Still, I hope this is something that gets corrected in future versions. The inconsistency between checkbox in the global settings and combo box on the actual grading page is a real faux pas in interface design.