Bug description 

At one "turn-change" it took quite a while, so I've saved (don't know when sadly) the game and reloaded it.

After that a lot of my tiles turned "grey" (as you will see in the attachment), like not everyone but sparse in my cities.

Contemporary Era

Japanese

Map size: Normal

Game speed: Endless

Singleplayer

Steps to reproduce 

Sadly I didn't quite paid attention on the steps, it was just an "end-turn" situation where I clicked on it and started to wait a long time.
Then I saved and reloaded the save and this happened.

Expected behavior

Which makes me think that this was the problem, I fear that my savefile got corrupted because of my actions above.

Thank you for your time!

Savegame: Japanese Turn 380.ctr