The old save game bug seems to have persisted. Upon loading a saved game all terrain from fog of war was now hidden on the map. Previously researched techs and their developments were not available (i.e. Had researched agriculture but it was now gone. Unable to build the advanced houses I had researched).

However, I did not have the save game issue with cities being missing.

How do you get to barracks research without any other research? You don't, it is a save game bug. The current research is still selected but I've got no save data on all my previous research discoveries.