Phaaryl Megalith unique map bugged

I hit all 5 monoliths / rune stones. The boss encounter for the map is not activating. Just watched a video of someone else doing it, can confirm I'm not doing anything wrong. The lightning and animation that precedes the encounter isn't happening either.

I portalled out to make a trade mid-map, and I'm guessing maybe that's what caused the problem. I also notice that the run stones don't show on my (full screen) map until I'm close, which is different than what I see in the video and different than how it was before I portalled out (I remember, before I reentered the map, the ones I had already clicked showing on the edge of the map when they were out of range).