Airship causing fatal error in one world; same airship works fine in another.

[RememberBB]

-Mod version 6.355

• Game version 1.12.2
• Forge version 14.23.5.2860
• No crash, fatal server error which boots me to the title screen

I have two worlds, a creative world and a survival world. I have a large airship in my creative world (circa 60,000 blocks) which I have attempted to recreate in my survival world. When I try to fly this airship in my creative world, it flies relatively smoothly. But on attempt to mount ship in survival world, a fatal error occurs, the server shuts down, and I am booted to the title screen, so not a crash. At first I thought it was because snow built up on the top, and when the ship became an entity the snow clashed with it and caused the problem. Then, I thought it was because the balloon limit in my survival world was 30,000 instead of the 100,000 in my creative world for some reason. But after some experimentation, I have concluded that neither of these are causing the problem, because it still happens. I will attempt to uninstall and reinstall the mod to see if that works, but I doubt it.

Update 1:
Uninstalling and reinstalling both DaVinci's and MovingWorld did not work. I also tried removing the shulker boxes and water in cauldrons and that didn't work. I made sure that airships still work in the world by testing with a small makeshift one, and they do. I will try two more things, if neither of them work, all I can do is wait for a developer response.

Update 2:
I tried flying my other airship, a smaller one, in my survival world and it flies fine. So now I'm starting to believe it must be a specific block that I have placed on the larger survival world airship that I did not place on the larger creative world airship, since the two airships are not identical. I will begin testing this later. I will find every block that I have placed on the survival airship that I did not place on my creative airship and go through them one by one on a small test airship to see if any of them cause a fatal error.

Update 3:
I realized that all 7 of the beds in the airship were regular beds, not the secured beds provided by the mod, so I tried replacing all of those regular beds with secured beds. This did not work. I also determined 9 blocks which were in the survival airship and not in the creative airship, and placed them on a small test airship. Unfortunately, it worked fine, meaning none of those blocks were specifically causing the error. I have one last idea, making every room identical to the creative world airship. If it doesn't work, I will need help in determining the cause of this error.

Update 4:
It didn't work. Please help.