I'm using FarPlaneTwo[fp2-0.0.1.612-1.12.2] with the latest version of Cubic Chunks and Cubic World Gen with Malisis Core[malisiscore-1.12.2-6.5.1], Mixin Compat[[MixinCompat-0.8]] and Forge Rocks [ForgeRocks-6.20.3-1.12.2-full] and I am having an issue where when I create a world everything is fine until I break a block and it says I have disconnected while in single player. Here is the log: https://pastebin.com/vxiwyCpj

this issue appears to be related to malisiscore(i don't even need to look at the logs, because i had the exact same issue) and there's not much you can do about it.

however, you can create a world with malisiscore and then right after the world is created exit the game(safely) and disable/delete malisiscore and all should work just fine.