When entering data for Ground Overlay Bounding Box coordinates, ArcGIS Earth validates if the data is compliant or not as a coordinate. If it is not compliant, it flags it in red for North, East and West, but not for South.
Note that the validation is rightly done (you cannot enter non compliant South coordinates). The data is just not flagged in red as it is for the other cardinal directions.
Thank you.
Thanks for your info, have created a earth issue to track this, will fix it in earth 2.2 release.