Breach Mechanic Didn't Spawn Any Mobs in 7 Waves

As the title suggests I just completed a tier 14 Arachnid Tomb where the breach was located in a small room adjacent to the main path to the boss. Nearby was an Expedition encounter and a Legion encounter (Which was in the leftmost room and was completed prior to starting the breach). I walked over every spawner on the ground and clicked the breach (Which was located in the large square room to the rightmost of the map overlay). Waited until all 7 waves were completed and not a single mob spawned. I got the 600+ graftblood, but no additional loot.

Hi,

can confirm this, had the same issue 5 minutes ago. Also a legion pile was near.
But i get gold, craftblood and a wombthing and some loot.