Note the missing unit/city/quest UI along the upper left side of the screen.  Reloading without restarting causes this.  Exiting then reloading brings it back.

We should see:

This happened occasionally when I first started playing LH.  It became more common, and in this game now it happens every time I reload without first exiting.

Settings: huge world, ridiculous world and AI sovs, my custom sov vs the 4 default empires, win7 64bit, currently turn ~100, but began to occur every time perhaps 30 turns ago.