Error appears on Survival and Creative. So if you change the textures of Minecraft PE with for example this texture pack: http://dokucraft.co.uk/portfolio/pocket-doku/
Netherrack will change into breakable static animated water. However if you deactivate water animation (using mods) the netherrack will appear normal. I don't know if an other block is effected (maybe one with lava).
Android and iOS users seem to occur the problem