TNT does not explode, cheats OFF

TNT does not explode, instead, when shot with a flame arrow it disappears and when lit by a flint and steel it catches on fire instead. It just burns endlessly like a normal non-consumable block (like netherrack) but the fire doesn't appear to spread to other flammable blocks. However, when I destroyed the tnt, it disappeared in a puff of fire as if it landed on fire and left invisible fire in the spot it occupied; I cannot see the fire but if I stand on that block I take damage (but don't catch on fire) and items burn up if dropped there, but the fire doesn't spread.