After defeating bosses in the Pale Heart in Overthrow, there is a chance bosses do not drop motes of light, or motes of primordial light, when the requirements are met for either. I am also part of this case. I have 16 motes of light ([spoiler]8 visions of traveler + 8 overthrow motes[/spoiler]), as well as 1 mote of primordial light, which should not be possible. Because of this, I cannot get the exotic weapon, Khostov, which the motes of light are needed for, and am currently softlocked. Looking online, I am not the only person who has this issue.