Similar thing happened to me and a few for a few of my guild mates. We have never had an issue before, but half of us got destroyed on wave 4.This was my first time failing it in the past 6 months. We usually get 22-28 shards. We got 10 this month.
The scenario was w/ ARC Trooper, Sergeant, Commander, Aalya Secura, Sentinel, Luminara that wrecked us. Apparently this is the "hardest" one to get. They all have the preloaded turn meter. My run went: I clicked the Hellfire tank... my tenacity down didnt stick on the ARC trooper ... I couldnt get ability block out ... he AOE dazed my Geos. Suddenly 2 more AOEs later. GG I lost.
I want to believe that there was a bug ... cause Im at 98/100 and the 2 shards are the only thing holding me back from JMK... I have all the gear and relics ready to go. However, most likely crap RNG.