how to get the last 2 shaper orbs?

i did elder 3 times, the first time it dropped the last memory fragment i obtained

how to proceed now to get the last 2?

I'm starting to think it's currently not possible. I've been stuck on 13/15 for this quest for the last two days now and I cant find the last two shaper orbs/memory fragments. Also, elder will not infect my t16 maps, not sure if that has something to do with it.

Same problem. I cant find my last fragment. I killed 5 Elders in red zone. Whats wrong?