Looks like I was wrong to complain about the Sha of Pride not being a guaranteed drop for runestones like Lei Shen. Hey, it is not the first time I was wrong and surely won't be the last. So I offer this as a public service announcement in case someone else was being grumpy like me when they got nothing off the so called "guaranteed" drop boss.
When you are on a quest to collect anything for the legendary quest line make sure to try and loot the boss, any boss, sometimes, albeit not often, the item is not automatically placed in your bags. It might be on the body. So when the boss died and I did not get anything I just left group after the LFR when I should have clicked on the boss, or chest, and seen if there was something there for me.
So if you are collecting, give it a try. Maybe, just maybe, what you are looking for might have not been automatically awarded to you. So those sha kills that I said were not guaranteed, there might have been something sitting there for me, I just never took the time to loot it myself. Next time I know better and will look. I suggest you do the same, it could speed up your quest, even one runestone faster.