Trying to create a course - but getting a straight line when selecting longer distances

None of the questions already asked are applicable to me.  I am trying to create a course that is from Orlando to Savannah GA. When I click the starting point and ending point, the app says that it is calculating, then creates a straight line.  If I choose a location that is closer to my starting point, it works fine.  It seems as if I get further away than a certain distance it reverts to a straight line.  Is this a limitation of the app? I am using the built in Topoactive maps from my Fenix 7x watch.  I paid for the North America drivable maps, but those don't show up in Explore - only the topomaps.