Tried three times (close program, relaunch, load) and the transition between 165 and 166 never completes. Nothing seems to happening on the screen, but the game isn't frozen. Where are the save files located so that I can upload the save?

On my Windows 10 machine, they are located at:  C:\Users\<MyUserName>\Documents\Humankind\Save_Files\*.ctr

Of course, your mileage may vary...

Ah... I should have been able to find that. Only thing I looked in My Documents was the My Games folder. Here is my save file: Ming Turn 165.ctr