[Can't earn G3 death marks]

Thank you, m friend.

[Can't earn G3 death marks]

So about a month ago. I was playing a nightmare mission and the G3 were starting to spawn but i went down after the first light flicker and first message from lotus(they never ended up spawning in). Ever since then, ive been unable to earn death mark from the invasions, however i am able to earn marks for zanuka just fine. Any help would be appreciated i just need the Brakk barrel. 

[Hey. Im new to this]

Anybody know of a good website to look for how much platinum certain items go for PS4 Users. Thanks in advance.