Failed to complete Abyss?

Can someone tell me what's going on? This happened to me twice. I run a Zana mission, I get about 3/4 of the way through the Abyss then it says "Mission failed. You failed to complete the Abyss." Is there a timer that it's not showing us or what?

There is no fixed timer, but if you're too slow following the crack or fail to kill most monsters from a pit spawn in time the Abyss will close. If you don't get an Abyssal Trove (or Abyssal Depth) it's a failed mission obviously.