I just checked the map and then the scenario. Both are displaying fine using the 2.02 edition(latest revision) and in using Windows 10.
Not sure what the issue is at this point fastphil. But willing to help where I can!
Assume your using 2.02 edition of RS. When you check help/about in the map editor or scenario editor does it say that? That is Rising Sun 2.02. Copywrite 2014 Matrix games? If you look at the individual scenario/map file does it give this date? Scenario: 12/14/1999 and the map: 9/25/2000??
If it does not sure what's going on.
I can zip my files and send them to you if you need. You may have a corrupted file or possibly corrupted game in some way.