Exalted Plains Riverside Garrison Rift Isn't There (DA:I)

So I'm working on the quest "Rifts on the Battlefield" in the Exalted Plains, and the rift that's supposed to be located at the Riverside Garrison near the north end of the map just isn't there. There's around three to four little green pools on the ground that usually mean an enemy is going to spawn, but no enemies spawn. All I get is two Shades that spawn every two minutes and start fighting the Orlesian troops that are nearby. I stand exactly where the marker for the rift is on thew map, but I can't see it. I can hear it, but there's nothing to click on. I thought it mgiht be below the building (because there are stairs going down), but no dice. Anyone else having this problem?

System Specs:

i5-3570k @ 3.4 GHz

Sapphire R9-290 4GB

2x4GB Ripjaw G.Skill RAM

Corsair AX860 80+ Platinum 860W PSU

Asus P8Z77-V Pro Mobo