Breach Collapsing?

Bit confused about the new breach mechanics.

I know what when you kill enough to fill the bar the breach stabilizes and spawns some rare monsters, but when I kill those, it says the unstable breach collapsed? Don't know if I'm doing something wrong or if it's just a wording issue.

Working as intended. After you kill the rare mobs, or Vrun (the boss) if he spawns, the Breach collapses, and you get drops after.