Here is an important update about the glitch behaviour:

1. Like I said the glitch appears right at the "seam" of the eastern and western borders of the map.
I tried to move my battleships along the seam and the glitch kept generating itself in that area.

2. It generates not only stretched polygons but also a fake terrain. Here is the screenshot:

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1672668120

The battleship is able to sail on that fake terrain but it "jumps" while sailing on it like a car on a bumpy road. As i see the fake terrain appears on water tiles while stretched polygons appear only on soil

3. When I load a savegame and there is no glitch (it starts after 2-3 turns) the game crashes right after I move my battleship to the problem area. It "blinks" black screen for a second and crashes. I can avoid crashes If I wait 2-3 turns for the glitch to appear and only then move my batteships to that area.

Here are the logs + SAVEGAME:
https://drive.google.com/open?id=1LzZ4o5_OSjO8s4qg4sSa1DpLRR2F70Nm


P.S. I need to mention in front that it is not a hardware issue. This glitch I found out only in Civ 6 at "the late game" period which is about after one week of play (more than 700 turns without the glitch).. I haven't experienced the stretched polygons problem in any other game. I tested my pc in furmark and other benchmarks with no errors or artifacts.

Another important thing to notice:
Today I loaded a save and tried "reveal all" command. The game crashed a few seconds after. It showed me "a natural wonder discovered" and then crashed. I tried three times and ended up with the same result.

I started a new game - Giant Earth with all nations and executed "reveall all". No crash. I played a few turns, hitting "reveal all" and still no crash.

It seems like the game generates some sort of bad tiles during the late period. They either cause that strange glitch with stretched polygons or a crash. May be entering a specific era is the reason. Entering a new era changes the look of buildings, traders, etc, so may be some tiles go crazy for some reason. And the game crashes as soon as they become visible to the player either with "reveal all" or by exploring tiles with units.

I hope this along with the savegame file will help to solve the problem since it is quite common one.

Guys, I would really appreciate if you check my savegame file. I'm just curious will you get the same glitch or not? Just go to Portugal area you will find two of my battleships there. (I play USA) Try to move them near Libson and lower to the west Africa coast. Just make a few turns and please post here whether you faced a game crash or stretched polygons.

Thanks for the detailed report and logs/save

I can't load this saved game (I don't have all DLCs neither R&F) but I'm interested in who can load it, and with which GPU and OS

I'll post your files in some other threads for more visibility.

and just for reference, you can load the saved game you've posted above on your computer ?

on this save the glitch appears after 2-3 turns and it crashes on reveal all ?

Gedemon, thank you I appreciate your help!

1. Yes, I can load the savegame easily. Sometimes the savegame might not load (stuck at loading screen with Roosevelt and text) but it seems like a random bug. Just need to make another attempt. I would say 9 times out of 10 the savegame loads successfully. It takes about 3-5 minutes to load.

2. Yes in that savegame glitch appears after 2-3 turns. Sometimes even after the first turn. As soon as AI finish his turn the glitch appears. It is a bit random I suppose it depends whether AI moves some units or not. Also, the glitch changes its "pattern" from turn to turn. And again I assume it depends on AI units' movement.

Yes, it crashes on "reveal all". I load the save and right after that I do "reveal all". The result is crash. Also, crash happens when I move units to the area of the visual glitch BEFORE it happens. When the glitch has happened the game does not crash and I can sail through the glitch with no problem.

--
Like I said before I started noticing the glitch way before the current game progress. It was about ~700 turn when I noticed it for the first time. I have played more than 150 turns with it. I did experienced a few crashes but not so often to be care about. May be it was more or less stable because I did not move my units to that area.

Ok, so I've just submitted a huge text to 2K with detailed description of the bug and random crashes. I provide them screenshot and dxdiag.txt file. I'm gonna keep you updated in case if 2K would reply with something important.

I invested a little bit more time trying to find the cause for crashes... Well, I tried to play with the glitch and ended up on turn 878. The game can't go further. Interesting fact is that it crashes always at the same point:

AI's turn is in progress and when it comes to ROME the game crashes...

I googled and found that many players have experienced the same issue. There was an official 2K message from support that they aware of the bug and they adviced to declare war on problematic nation. That did not help me although it worked for some folks.

Also, some new info about the graphical glitch.... I found a few topics with reports about the same problem. One player wrote that the game has some problems with accessing to RAM/VRAM which might cause those artifacts as well as crashes.

All of that leads to a conclusion that has already been confirmed. The crash problem does not relate to a mod, same goes for graphical artifacts.

The reply from 2K finally has been received. Nothing interesting, pretty standart. "Reinstall game/windows/drivers, etc". They don't even read my text because I wrote that I tried to reinstall all of it. Of course they want me to disable the mods. So, no help from to 2K...