I'm guessing they don't have a 30% drop rate like a regular hard node? 8 runs and zero bonus shards.... The chances of that are 0.019% or 0.00019 (70% chance of not getting one, 24 times) Come o...
I would just like to suggest (as was suggested much earlier) that there is the possibility that there are two calculations in play per drop. The first could be a 30% chance check to determine if there is a bonus shard drop (of 2 shards) - the second, simply to determine which of three possible shards they are. So the OP was 0 for 8, not 0 for 24.