Phase through blocks at head height

Game keeps letting the player's head "phase" through blocks, either by walking into blocks 1 above ground or jumping into blocks above the player. Guard rails on bridges made of any block that are a space above the floor, for example, don't work because I can just walk right through them, and can jump into ceilings. Bottom half of a player isn't affected, and this is temporarily fixed by quitting and re-entering the world, but has persisted for a few days