I have a 3x3 rail spiral, and one block stack breaks the rail when I enter the game. I have tried using both powered and un-powered rails, and assume it occurs when I enter the game because I am able to go and pick up the rails.

it is only on the one x,y coordinate. I don't have a photo (sorry).

The block is a middle block, not a corner. The block is powered by a stack of redstone torches and redstone dust alternating up the stack. it's a wood block. There doesn't appear to be any rails popping up anywhere else in the realm, with the exception of one additional rail on the stack that is a few blocks over at the bottom of the spiral, which expands at the bottom. The blocks that the rails are on are spaced 2 blocks high by the spiral, which is consistent on all sides of the spiral. The block that is breaking rails is adjacent to a torch or redstone dust, not a block that the torch or dust is on. the outside of the spiral is just open.

I will try to attach a picture later.