Why doesn't the Present Location button cause me to see my position on the map?

You need to have location services enabled in order for the current position feature to work.  

For PC Users:

Windows 10: Select the Start icon on your taskbar, and then select Settings > Privacy > Location.

Windows 10 Mobile: On the Start menu, swipe over to the "All apps" list and then select Settings > Privacy > Location.

 

For Mac Users:

Please see this article:  About Location Services in OS X and Safari