This note is in the wrong place and should be a mile east, but I digress, the issue might be because Ramsey County refers to this road both with the directional and without, and also uses parcel addresses with the directional and without. I emailed them to see how they want this road referred to.

Your solution for the time being is to update Sunnyside's "Contact Us" page to include the directional, and tell people to include the directional (MapQuest has both versions and the directional takes you to the school), because the parcel the school sits on uses the directional in its property address.