Is the MLA dead....or just resting?

The allocation has long been an equal share to all buyers, equally distributed amongst all sellers.  The market is evaluated roughly every 20 mins and is matched in that way, with any excess beyond what someone wants to buy or sell being equally distributed amongst everyone else.

That said it's a two phase process.  The buyer and sellers are matched, and then dropped into a queue to be processed.  If the sale fails to go through for whatever reason, perhaps because the buyer had another purchase go through in parallel that used up the funds, or if there is a transient error in the system, then some of those trades may fail to process correctly leading to unequal distributions.  Any failed trades are then picked up the next time the market runs, treaded as if they were new buy / sell orders, and run through that matching algorithm again, so they could end up going to different people.