Mobs do not drop spawned equipment

To the best of my knowledge, there should be an 8.5% chance of a weapon drop every time I kill a monster equipped with one. However, I have not once collected an iron sword or shovel from a zombie, a golden sword from a zombie pigman, a bow from a skeleton, or a stone sword from a wither skeleton throughout all of my playing MCPE (which includes running tests on hundreds of skeletons).
I would very much appreciate if this bug is fixed, it's one of those little features that make MCPE so enjoyable!