interesting... can i ask which region you guys play on?
Jon, apart from some obscure bug or regional drop variation (which seems very unlikely but not impossible i guess) the fact you're AK15 i'm gonna make an educated guess that you have been killing a lot of mobs in suramar in your time, perhaps the charm is somewhere in your bank already and you need to talk to thingy or have it on you to get the drop?
idk - if you're certain you don't have the charm already (which seems like the worst rng ever) and downfall aint dropping the thing, it might be worth opening a ticket and asking a GM.. they might give you the copy+paste "go read community forums for tips we can't help" nonsense so maybe direct them to your post in this forum specifically (perma-link via the #postnumber in the top right) and insist that you feel like something is bugged.. hopefully they can at least let you know if something has gone wrong somewhere