I have created a bug tracker ticket for the problem of people being unable to see some/all of the black circles in the last phase of the Nekron fight. If you are having the problem, or have any ideas about what causes it please let the devs know https://dgcissuetracker.com/browse/DC-1188
TBH that's good because the ones that I have been in had black circles overlapping each other all the way across the screen.
Couple of groups i've been in, the circles do appear, but they appear in the air/mid-air, so they are hard to see or they appear to be in a place but their AoE seems to be uncentered, so it appears the character is standing out of the black but it still takes damage.
I'm in PS4 and not see all the holes and not always. What I do is follow someone who can see them, but I can not pick up fast if someone die because i dont know if they are inside, until someone says. Some partners have this problem too, and all are in PS4.
Im having the same problem (EUPC). After I die, people keep asking me why I didnt move out of black whole but there was nothing at my screen. Sometimes when I put camera angle to look at my toon from above I can see black whole spawned at my head or above me but there is no way to see it if you are using normal camera angle. Same thing happens at Brother Blood fight in UM but there is at least sound effect to let you know you need to move out of the blood pool area there.
IMPORTANT! Try this seems to work, I worked yesterday but not if it was a coincidence ... they was told me it was fixed so... Go to SETTINGS to the VIDEO tab and then move graphics up. If tested and confirmed resolved, pls, say that. Then everyone knows the solution.