Make fragment reward type drop something other than atziri fragments

I did 100% delirium map with 5xfragment rewards, received rewards 14 times. And only I got is shitloads of sacrifice fragments and some mortal. Zero Shaper, Elder or Sirus fragments. And probably never got these. I haven't found any info about drop rates. Probably you can't get something else. Maybe other fragments should added to reward pool too?