Quitting and saving while stone generator with pistons pushing the stone out (and moss farm) was running caused unbreakable stone blocks to form. These show no animation of breaking, blocks behind them are broken instead. The player can stand on them, dropped items and water collide with them but arrows do not. Blocks cannot be placed inside them, but can be placed through them (as an adjacent block on the opposing side). Pistons cannot push them or through them (they are unmovable).

Additionally, invisible blocks have formed which are opposite in effect: player and items can move into/through them, but blocks still cannot be placed inside them and water cannot move through them.

A third type of stone block, which collides with water and the player but can have blocks placed inside them, have also formed along the border of the adjacent chunk. Placing blocks inside them and then removing those blocks does not remove these phantom stone blocks, they persist.

Leaving simulation area while the stone generator is running and while off both do not resolve the issue. Reloading the world, rebooting minecraft, and rebooting the device do not resolve the issue. These blocks cannot be turned into moss using bonemeal. Duplicates of the world maintain the unbreakable blocks.