Breach Map - No Monster Spawns, Path Didn't Unlock

I just entered a Breach map. However, upon entering, no monsters spawned at all, which made it impossible to progress or unlock the rest of the path. I waited for a while and explored the area thoroughly, but nothing triggered.

This seems like a bug preventing the event from progressing. I couldn't complete the encounter, and the map essentially became a dead end.

Here's a screenshot of the issue: