This issue has haunted me for years, and I finally decided to make an account to post in a fleeting hope any devs care or are watching. I know a lot of people are having a variety of issues they've outlined in the thread, but the core issue is GS Coastal Flooding causes a predictable and reproducible crash on these larger map sizes. I understand this is exposed by mods, but the larger map sizes enabled by mods are the reason I've played thousands of hours in the series.
So I get that it's a problem I create when I add these mods, but it's an easily reproduced memory exception causing predictable crashes. There is a bug in the game exposed here. Which I get happens with the massive amounts of code required to make a game like this possible, but what bothers me is the general apathy from any one at Fireaxis. If it's something being worked on, tell us it's being worked on; if you're aware of the issue but it's on the backburner, tell us you're aware of it; if it's not an issue that is going to be addressed, please tell us so I can stop wasting my time holding out hope Civ 6 will ever be able to run these mods.
Civ 6 was advertised to be the most moddable and mod friendly version we had ever seen. So far all I've gotten is hundreds of hours of debugging a broken base game that can't run the only mod I want to run. If the bar has sunk this low that I can't play on a map bigger than 12 players, I'll just go back to Civ 5 that I know can at least menially function for a full game. This casts serious doubt in my mind about any future Civ games because of how frustrating it is to see basic issues like this summarily ignored.