Whenever the ancient tomb shows up, it prompts the written in stone quest, but the next turn, regardless of everything else, the tomb will despawn, causing the gaim to fail the quest and forcing me to sacrifice a tile. I've been able to prevent the tomb from spawning by reloading auto saves, but I can't ever even start the quest. I'll buy an explorer in the nearesy city, sometimes a turn in advance and wait for it to spawn, but the game won't let me excavate it at all. It just clogs up my territory and causes settling problems. Does anybody know how to fix this?