Silent Cave Unique endgame map failing to reward atlas skill points

I completed two separate versions of the above unique map that claimed it would award me 2 atlas skill points upon my first completion, yet neither time has done so.

The first time i did not fight all rare essence monsters before fighting the central boss and thought that may have been the issue.

This time I killed all rare essence monsters and the central boss; 4 greater essences dropped but no atlas skill book still.